# PCI-e 3.0 x8 may not have enough bandwidth for RX 5500 XT



## IceShroom (Dec 19, 2019)

As title suggest, RX 5500 XT 4GB may be bottlenecked by PCI-e 3.0.
Here is a article in (german) : https://www.pcgameshardware.de/Rade...pecials/PCI-Express-3-vs-PCI-E-4-GPU-1339415/


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## Hyderz (Dec 19, 2019)

interesting...


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## Khonjel (Dec 19, 2019)

Aw. Since 5500 XT is only a x8 card instead x16 card. I just did a cursory glance on its reviews so this was a surprise. Guess it's an all around bad buy compared to GTX 1600 series.

Lol. What was AMD thinking? That people were gonna pair these xards with X570 systems?


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## londiste (Dec 19, 2019)

Looking at the tested games, all are run with max details. Is this a VRAM-limited situation? That would very clearly explain the big differences because card would need to use system RAM and more bandwidth definitely benefits there.

I wonder if the results are same for 8GB cards?


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## INSTG8R (Dec 19, 2019)

Yeah budget 4GB card further hobbled by x8 interface it can apparently saturate, which I have to say is a first. W1Z has regularly tested PCI bandwidth and its effects which for years ha# been barely #how any real losses.



londiste said:


> Looking at the tested games, all are run with max details. Is this a VRAM-limited situation? That would very clearly explain the big differences because card would need to use system RAM and more bandwidth definitely benefits there.
> 
> I wonder if the results are same for 8GB cards?


I saw some charts earlier it was not that much higher but the lines we’re definitely not having the same issue


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## Hyderz (Dec 19, 2019)

battlefield v has a massive increase


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## Deleted member 67555 (Dec 19, 2019)

It really does seem like it's being held back by the memory... What an awful thing to do.


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## londiste (Dec 19, 2019)

INSTG8R said:


> Yeah budget 4GB card further hobbled by x8 interface it can apparently saturate, which I have to say is a first. W1Z has regularly tested PCI bandwidth and its effects which for years ha# been barely #how any real losses.
> 
> I saw some charts earlier it was not that much higher but the lines we’re definitely not having the same issue


Oh, you are right. I read the graphs wrong. For some reason I read 8GB cards as 5700 
8GB versions do gain from PCIe 4.0 but not to the same degree as 4GB variants.


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## potato580+ (Dec 19, 2019)

tgis card targeting to competed with 1650super, sadly amd failed this time, 5500 xt is such a waste, it even cant compete with old gtx1060/rx480, and the price seems pretti strange at my country, $220 for an newcard which have same performance as old $60 rx480, no thx,unless it set on $150 i would probably pay for it, just for testing


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## IceShroom (Dec 19, 2019)

potato580+ said:


> tgis card targeting to competed with 1650super, sadly amd failed this time, 5500 xt is such a waste, it even cant compete with old gtx1060/rx480, and the price seems pretti strange at my country, $220 for an newcard which have same performance as old $60 rx480, no thx,unless it set on $150 i would probably pay for it, just for testing


What was the price for GTX1060/RX480 when it was new??


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## potato580+ (Dec 19, 2019)

IceShroom said:


> What was the price for GTX1060/RX480 when it was new??


they were rarely on new stock these day, but based on my country pricetag, you can just grab rx590 for an $200, or even saving few buck by picking 1650 super, i strongly recomend 1650super this time, since it was more power efficent yet good performance


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## IceShroom (Dec 19, 2019)

potato580+ said:


> they were rarely on new stock these day, but based on my country pricetag, you can just grab rx590 for an $200, or even saving few buck by picking 1650 super, i strongly recomend 1650super this time, since it was more power efficent yet good performance
> View attachment 139841


Well that chart is old and for RX 5500 not XT. Here is new chart and here GTX 1650 Super is slower than RX 5500 XT.
@W1zzard can you look into this PCI-e  4.0 x8 vs PCI-e 3.0 x8 for RX 5500XT on AMD X570??


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## INSTG8R (Dec 19, 2019)

londiste said:


> Oh, you are right. I read the graphs wrong. For some reason I read 8GB cards as 5700
> 8GB versions do gain from PCIe 4.0 but not to the same degree as 4GB variants.


Yeah there's been quite alot of surprise with the 4GB card. They literally hobbled it in almost every way possible.


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## Vayra86 (Dec 19, 2019)

Those are some serious gaps. Damn


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## Vya Domus (Dec 19, 2019)

It's definitely something else other than the PCI-e bandwidth, there is literally no other card that shows this behavior not even the 5700XT.


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## ratirt (Dec 19, 2019)

INSTG8R said:


> Yeah budget 4GB card further hobbled by x8 interface it can apparently saturate, which I have to say is a first. W1Z has regularly tested PCI bandwidth and its effects which for years ha# been barely #how any real losses.
> 
> 
> I saw some charts earlier it was not that much higher but the lines we’re definitely not having the same issue  View attachment 139840


What is the "Y" Axis represent? delay or FPS or something else like bandwidth? It s not clear to me and the graph doesn't seem to have any map-key and I'm not sure if I read id correctly.


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## londiste (Dec 19, 2019)

Vya Domus said:


> It's definitely something else other than the PCI-e bandwidth, there is literally no other card that shows this behavior not even the 5700XT.


5700XT has twice the PCIe lanes and twice the memory. At the same time article addresses the memory part where PCIe 3.0 vs 4.0 results are pretty close with 8GB of memory. Low-end cards are often enough with PCIe x8 but 5500 is the first one with 4.0 capability so there is nothing to compare this to.

When VRAM runs out, the data will get put to system RAM and accessed over PCIe, doubling that bandwidth is expected to make a huge difference and it does seem to do exactly that.


ratirt said:


> What is the "Y" Axis represent? delay or FPS or something else like bandwidth? It s not clear to me and the graph doesn't seem to have any map-key and I'm not sure if I read id correctly.


Frametimes in milliseconds. Less is better and FPS is 1000/Frametime in ms - for example at 25ms frametime, 1000/25 = 40 FPS.


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## INSTG8R (Dec 19, 2019)

ratirt said:


> What is the "Y" Axis represent? delay or FPS or something else like bandwidth? It s not clear to me and the graph doesn't seem to have any map-key and I'm not sure if I read id correctly.


Yeah sorry I can’t even give you the source I got it from a discord group when we all got suspicious someone posted that graph. Zooming in the Y axis appears ro be FPS but even then the green data point doesn’t make sense?


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## Vayra86 (Dec 19, 2019)

INSTG8R said:


> Yeah sorry I can’t even give you the source I got it from a discord group when we all got suspicious someone posted that graph. Zooming in the Y axis appears ro be FPS but even then the green data point doesn’t make sense?



Frametime lower is better; that is why the green one (lowest spec) is so spiky, it struggles visibly. The other setups lose performance, but are not 'stuttery'.

VRAM being low AND the PCIe bandwidth combined just creates a horrible cocktail... Though it does also seem like a driver/efficiency problem, it should be much more consistent under 3.0 given the data that is transported.


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## arbiter (Dec 19, 2019)

Vayra86 said:


> Frametime lower is better; that is why the green one (lowest spec) is so spiky, it struggles visibly. The other setups lose performance, but are not 'stuttery'.
> 
> VRAM being low AND the PCIe bandwidth combined just creates a horrible cocktail...



Yea it would seem to be the memory is getting maxed out which then its calling upon system memory to act as vram. If that is the case that would explain why the frame times are so bad since its maxing bus it has out.


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## Vayra86 (Dec 19, 2019)

arbiter said:


> Yea it would seem to be the memory is getting maxed out which then its calling upon system memory to act as vram. If that is the case that would explain why the frame times are so bad since its maxing bus it has out.



Driver fix: lower FPS... Right now it just keeps running into that wall like a blundering idiot.



INSTG8R said:


> Yeah like I said I just used the first source available showing it tested in different PCI speeds it makes much more sense now. Doesn’t change the fact AMD really hobbled this card to the point of almost being pointles.



Yeah if this is how they intended to sell us PCIe 4.0 .... fail


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## INSTG8R (Dec 19, 2019)

Vayra86 said:


> Frametime lower is better; that is why the green one (lowest spec) is so spiky, it struggles visibly. The other setups lose performance, but are not 'stuttery'.
> 
> VRAM being low AND the PCIe bandwidth combined just creates a horrible cocktail...
> 
> View attachment 139852


Yeah like I said I just used the first source available showing it tested in different PCI speeds it makes much more sense now. Doesn’t change the fact AMD really hobbled this card to the point of almost being pointles.


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## londiste (Dec 19, 2019)

Wolfenstein Youngblood at Mein Leben! settings (which is not maxed if I remember correctly) consumes between 5-6 GB of VRAM. On a 4GB card that extra GB or two that does not fit into VRAM must be accessed over PCIe bus.


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## Flaky (Dec 19, 2019)

The main takeaway from the article seems to be "don't set detail level so stupidly high that it exceeds card's vram". The only result that seems anomalous is one from Far Cry.

RX 460/550/560 also did have x8 link max, and it seems to be the new norm for mid-end cards from AMD.
One of the reasons is GPU link in their APUs - it is exactly x8. As they will be put together in many laptops, extra 8 lanes would be often wasted anyway.


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## Vayra86 (Dec 19, 2019)

Flaky said:


> The main takeaway from the article seems to be "don't set detail level so stupidly high that it exceeds card's vram". The only result that seems anomalous is one from Far Cry.
> 
> RX 460/550/560 also did have x8 link max, and it seems to be the new norm for mid-end cards from AMD.
> One of the reasons is GPU link in their APUs - it is exactly x8. As they will be put together in many laptops, extra 8 lanes would be often wasted anyway.



Its been said many times, but VRAM demands have increased faster than core grunt demand. Processing power in consoles is a slow crawl, but their VRAM also exploded to 6GB and will be pushed further soon.

Its a simple 1+1=2.... even with playable settings you can exceed card VRAM.

Inb4 the number cruncher telling us its not true and games usually have enough with 3/4GB...


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## Vya Domus (Dec 19, 2019)

If these games consume more VRAM than there is available on the card then this isn't actually about the PCI-e bandwidth, is it ? This was spun off in the most stupid way that I can think of.

You can clearly see in those graphs that there is an obvious separation from the 8GB and the 4GB results and that this has almost nothing to do with the PCI-e connection speed. When you need to swap memory contents obviously a higher transfer rate between the host and card is going to be beneficial.

This card has enough PCI-e bandwidth, what it doesn't have is enough memory.


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## Kissamies (Dec 19, 2019)

I'm not buying that. Even with RTX 2080 Ti there is little to none penalty from 3.0 x8.









						NVIDIA GeForce RTX 2080 Ti PCI-Express Scaling
					

It takes a lot of bandwidth to support the fastest graphics card, especially one that can play anything at 4K 60 Hz, with an eye on 120 Hz. The GeForce RTX 2080 Ti could be the most bandwidth-heavy non-storage PCIe device ever built. PCI-Express gen 3.0 is facing its design limits.




					www.techpowerup.com


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## ratirt (Dec 19, 2019)

Vya Domus said:


> If these games consume more VRAM than there is available on the card then this isn't actually about the PCI-e bandwidth, is it ? This was spun off in the most stupid way that I can think of.
> 
> You can clearly see in those graphs that there is an obvious separation from the 8GB and the 4GB results and that this has almost nothing to do with the PCI-e connection speed. When you need to swap memory contents obviously a higher transfer rate between the host and card is going to be beneficial.
> 
> This card has enough PCI-e bandwidth, what it doesn't have is enough memory.


I kinda agree. Bandwidth is a different thing from VRam capacity. Although you can see that the 4gb version performs better when using PCIe 4.0 than 3.0. Maybe the greater bandwidth can compensate for the lower capacity of VRam. Also there is not much difference in 8GB when used with both version of PCIe. I think it is actually good that it works better on the version 4.0. This means that there is some sort of improvement and maybe within time switching to PCIe 4.0 will be justified.


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## ShurikN (Dec 19, 2019)

Chloe Price said:


> I'm not buying that. Even with RTX 2080 Ti there is little to none penalty from 3.0 x8.
> 
> 
> 
> ...


A 2080Ti will also never run out of VRAM. A 4GB card might.



Vya Domus said:


> This card has enough PCI-e bandwidth, what it doesn't have is enough memory.


The card doesn't have enough VRAM therefore needs additional PCIe bandwidth to compensate.
I mean how do you explain the differences in 4GB results. Some of which are insanely large. This one is 20ish%. That's in a different product category.


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## Kissamies (Dec 19, 2019)

ShurikN said:


> A 2080Ti will also never run out of VRAM. A 4GB card might.


GTX 980 has 4GB as well.









						GeForce GTX 980 PCI-Express Scaling
					

PCI-Express x16 3.0 is well established in the market, and the majority of gamers are using the interface. But what happens if you end up in a slot-bandwidth-constrained situation? We are testing NVIDIA's latest GeForce GTX 980 flagship in 17 games, at four resolutions, including 4K, to assess...




					www.techpowerup.com


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## ShurikN (Dec 19, 2019)

Chloe Price said:


> GTX 980 has 4GB as well.
> 
> 
> 
> ...


That testing was done exactly 5 years ago. Games have become more demanding.


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## Kissamies (Dec 19, 2019)

ShurikN said:


> That testing was done exactly 5 years ago. Games have become more demanding.


I knew that the reply would be something like that. 









						NVIDIA GeForce GTX 1080 PCI-Express Scaling
					

In this article, we investigate how performance of NVIDIA's GeForce GTX 1080 is affected when running on constrained PCI-Express bus widths such as x8 or x4. We also test all PCIe speed settings, 1.1, 2.0, and 3.0. One additional test checks on how much performance is lost when using the...




					www.techpowerup.com
				




With 1080, the same "8GB is enough"?


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## Vya Domus (Dec 19, 2019)

ShurikN said:


> The card doesn't have enough VRAM therefore needs additional PCIe bandwidth to compensate.



Nothing will ever compensate for the lack of VRAM, the 12 GB/s PCI-e transfer rate will never make up for the 200+ GB/s the VRAM is capable of. For all intents and purposes the performance will still degrade in a noticeable manner irrespective of the PCI-e bandwith.

I find it really strange that instead of saying PCI-e 4.0 brings some slight advantage to cards that are VRAM limited, which is the reality here, this was twisted into "AMD made a PCI-e limited card".


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## ShurikN (Dec 19, 2019)

Chloe Price said:


> I knew that the reply would be something like that.
> 
> 
> 
> ...


I'm not sure you're getting the point. Every testing was done on a flagship card at the time that had the highest amount of VRAM of that time. That none of the games could max out.



Vya Domus said:


> I find it really strange that instead of saying PCI-e 4.0 brings some slight advantage to cards that are VRAM limited, which is the reality here, this was twisted into "AMD made a PCI-e limited card".


In the 4GB case, the advantage was not slight. This would most likely not happen if the cards were x16


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## Vya Domus (Dec 19, 2019)

ShurikN said:


> This would most likely not happen if the cards were x16



This is the wrong conclusion, this would have not happen if there was more VRAM. You can see that even under PCI-e 4.0 (the equivalent of x16 under PCI-e 3.0) there's still a gap between it and the 8GB version, the root of the problem is the amount of VRAM there is no going around it.


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## Kissamies (Dec 19, 2019)

ShurikN said:


> I'm not sure you're getting the point. Every testing was done on a flagship card at the time that had the highest amount of VRAM of that time. That none of the games could max out.


I do get exactly the point. And they are still fully comparable to today's cards. Just like my 980 Ti can be compared to 1660 Super/Ti, both have similar performance and even the memory amount is the same.

1080 was released in 2016, Mirror's Edge Catalyst from that year for example can utilize more than 6GB.


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## ShurikN (Dec 19, 2019)

Chloe Price said:


> I do get exactly the point. And they are still fully comparable to today's cards. Just like my 980 Ti can be compared to 1660 Super/Ti, both have similar performance and even the memory amount is the same.
> 
> 1080 was released in 2016, Mirror's Edge Catalyst from that year for example can utilize more than 6GB.


Everything you said would make sense if all the testing was done on the same set of games. That 980 with 4GB was tested with games that couldn't max out it's VRAM at the time. 5500XT was tested with games that can. Your 980Ti CAN be compared to 1660 because at 1080p you are never going to run out of VRAM. And just because the game utilizes 6GB does not mean it needs 6GB. In the case of 4GB cards, more often than not, you need over than 4GB.


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## Kissamies (Dec 19, 2019)

I give up, this is like playing chess with a pigeon.


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## EarthDog (Dec 19, 2019)

TL DR - In my testing of 4GB and 8GB cards, we saw significant differences in results in Forza, BF V, Far Cry 5, and SOTR (using default ultra settings, 1080p).

EDIT: It is interesting AMD set up the card this way...essentially shooting themselves in the foot with many users running PCIe 3.0 systems and wanting the budget card (how many people are rocking a brand spanking new X570 motherboard with PCIe 4.0 and buying an entry level GPU?)

This seems to be caused by the swapping of data when the vram is full.. yikes. Why did they do this to a 4gb card? Makes more sense to do it to the 8gb card where the data transaction are less..yikes.


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## W1zzard (Dec 19, 2019)

londiste said:


> When VRAM runs out, the data will get put to system RAM and accessed over PCIe, doubling that bandwidth is expected to make a huge difference and it does seem to do exactly that.


That


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## Vya Domus (Dec 19, 2019)

Chloe Price said:


> I give up, this is like playing chess with a pigeon.



This whole thread is like an insult to all common sense. The 4GB card runs out of VRAM, PCI-e 4.0 helps with this somewhat, that's all there is to it, there is nothing here that we haven't seen before.

Everyone is just out of their mind, suggesting that AMD made all of this on purposes for their X570 motherboards and whatnot. In numbs my mind reading these conspiracy theories.

4GB are starting to be a significant constraint. No wonder, something like an R9 290 shipped with 4GB as standard what, six years ago ? It's time to move on.


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## EzioAs (Dec 19, 2019)

londiste said:


> 5700XT has twice the PCIe lanes and twice the memory. At the same time article addresses the memory part where PCIe 3.0 vs 4.0 results are pretty close with 8GB of memory. Low-end cards are often enough with PCIe x8 but 5500 is the first one with 4.0 capability so there is nothing to compare this to.
> 
> When VRAM runs out, the data will get put to system RAM and accessed over PCIe, doubling that bandwidth is expected to make a huge difference and it does seem to do exactly that.
> Frametimes in milliseconds. Less is better and FPS is 1000/Frametime in ms - for example at 25ms frametime, 1000/25 = 40 FPS.



Oh, ok. This makes sense based on what (little) knowledge I have in CA.


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## HD64G (Dec 19, 2019)

Vya Domus said:


> This is the wrong conclusion, this would have not happen if there was more VRAM. You can see that even under PCI-e 4.0 (the equivalent of x16 under PCI-e 3.0) there's still a gap between it and the 8GB version, the root of the problem is the amount of VRAM there is no going around it.


I think that many of the modern games ask for system RAM to compensate for any lack of VRAM. So, when 5500XT is connected via PCI3 X8, when it tries to get to the system RAM using that it slows down much more than when it asks for RAM via the PCIE4. My 5c.

UPDATE: Some seem to have posted the same reason for it already, although somewhat reverse-wise. Didn't read that but good for the forum to solve those tech mysteries soon enough.


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## ShurikN (Dec 19, 2019)

Vya Domus said:


> Everyone is just out of their mind, suggesting that AMD made all of this on purposes for their X570 motherboards and whatnot. In numbs my mind reading these conspiracy theories.


Literally only one post in this entire thread suggested that, and more as a joke than anything else.


Vya Domus said:


> The 4GB card runs out of VRAM, PCI-e 4.0 helps with this somewhat, that's all there is to it, there is nothing here that we haven't seen before.


Which is exactly what everyone was saying. And that it's married to an X8 bus doesn't help as well.


Chloe Price said:


> I give up, this is like playing chess with a pigeon.


Hey you can identify as a pigeon, owl or an AH64 Apache, who am I to judge...


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## TheoneandonlyMrK (Dec 19, 2019)

Vya Domus said:


> If these games consume more VRAM than there is available on the card then this isn't actually about the PCI-e bandwidth, is it ? This was spun off in the most stupid way that I can think of.
> 
> You can clearly see in those graphs that there is an obvious separation from the 8GB and the 4GB results and that this has almost nothing to do with the PCI-e connection speed. When you need to swap memory contents obviously a higher transfer rate between the host and card is going to be beneficial.
> 
> This card has enough PCI-e bandwidth, what it doesn't have is enough memory.


+1x10


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## GoldenX (Dec 19, 2019)

It's something we see on yuzu, PCIe bandwidth can be saturated (even 3.0 16x) when you do many RAM<>VRAM copies, like when you run out of VRAM.
This is normal behaviour, and a very stupid way to make people look at PCIe 4.0.

What's with this tendency to give cheaper cards less PCIe lanes? We had 16x since the first days on Geforce 6, not we get nerfed with 4x and 8x cards.


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## ppn (Dec 19, 2019)

PCIE4 can help,
exactly 4 352 MB total VRAM, 4096+256MB for 224+14GBs
with PCIE3 can be saturated by only 128MB less, 4 224 MB, 224+7GBs

so they found the perfect example that used 128-256 too much more than 4352 MB, and PCIE3 latency manifested noticeably.


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## IceShroom (Dec 19, 2019)

GoldenX said:


> It's something we see on yuzu, PCIe bandwidth can be saturated (even 3.0 16x) when you do many RAM<>VRAM copies, like when you run out of VRAM.
> This is normal behaviour, and a very stupid way to make people look at PCIe 4.0.
> 
> What's with this tendency to give cheaper cards less PCIe lanes? We had 16x since the first days on Geforce 6, not we get nerfed with 4x and 8x cards.


Then RX 5500 XT would have been even more expensive.


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## EarthDog (Dec 19, 2019)

IceShroom said:


> Then RX 5500 XT would have been even more expensive.


Would it though? If I was AMD, the pittance it takes to run x16 traces and the performance improvements on 4GB cards that run out of VRAM is worth it. For the 8GB card it still helps... 

Win win... this move is really questionable considering the results of the 4GB card in VRAM hog titles.


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## GoldenX (Dec 19, 2019)

Inb4 people forgets the GT1030 suffers the same problem.


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## Assimilator (Dec 19, 2019)

So AMD's lack of good delta compression finally bites them.



GoldenX said:


> Inb4 people forgets the GT1030 suffers the same problem.



People aren't expecting playable framerates on a 1030. Take your whataboutism elsewhere.


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## GoldenX (Dec 19, 2019)

Assimilator said:


> People aren't expecting playable framerates on a 1030. Take your whataboutism elsewhere.


That's not an excuse. It's a Pascal like the rest.


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## Flaky (Dec 19, 2019)

GoldenX said:


> That's not an excuse. It's a Pascal like the rest.


Look around and see where GP108 does appear most often.


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## GoldenX (Dec 19, 2019)

My point is, no one is excused for this crap (well, maybe Intel, for now.). Those GPUs are already dirt cheap to produce, and I bet the savings in PCIe lanes are marginal at best. Sounds more like AMD and Nvidia found a new way to make people look at low/mid end GPUs with more VRAM, by artificially limiting their bandwidth.
Else, who would get the 8GB version of the 5500?


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## SomeOne99h (Dec 19, 2019)

It could be a bug in the card's BIOS that affects the card's performance in certain systems/chipsets? Right?


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## Zubasa (Dec 20, 2019)

Assimilator said:


> So AMD's lack of good delta compression finally bites them.


There is also driver optimizations such object culling matters a lot when you are vram limited.
It isn't as clear cut as just nVidia having better compression. Here are cases of the 1650 Super actually fare worse in 1440p while it fared better the 5500XT 4GB in 1080p.

















Assimilator said:


> People aren't expecting playable framerates on a 1030. Take your whataboutism elsewhere.


People were definitely expecting playable fps from 1050 ti and many of those were 8x cards.
This is also true for 1650.
So all of a sudden these lowest end GPUs gets "bottlenecked" by the pcie bus while every thing else isn't?


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## EarthDog (Dec 20, 2019)

GoldenX said:


> Else, who would get the 8GB version of the 5500?


Those who want to play certain titles that use more than 4gb of vram... more titles every month can... vram use isnt going down...


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## ratirt (Dec 20, 2019)

Not sure what's the problem here with this discussion. Get an 8GB card and the problem is solved. Besides, some argue that it is unforgivable to limit cards to x8 PCI? If the PCIe 3.0 x8 is the maximum the card can utilize, that is weird. Maybe it is bios problem. Besides do you really need more than 3.0 x8? Because I've been looking over some benchmarks measuring PCIe bandwidth affecting gameplay and the difference wasn't there between x8 and x16. Maybe now it is changing? I think the lack of VRAM is the issue not bandwidth because when you get an 8GB card the problem is gone. Using system memory instead of VRAM is always slower no matter what PCIe lanes you get.


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## biffzinker (Dec 20, 2019)

ratirt said:


> Well, PCIe 4.0 x8 has the same bandwidth as PCIe 3.0 x16 so there is not bandwidth constraints.


Who is going to pair a midrange RX 5500 4GB card with a X570 mainboard just for PCIe 4.0?


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## R0H1T (Dec 20, 2019)

Aren't they testing the pcie 3.0 runs on 9900k & the 4.0 runs on Ryzen 3xxx if so how is this Apples to apples?


biffzinker said:


> Who is going to pair a midrange RX 5500 4GB card with a X570 mainboard just for PCIe 4.0?


Depends on what you're doing with it, are you telling me people don't pair a TR (or Intel HEDT) with Nvidia's mid range xx50 cards? This card may simply be used for driving the display & occasional gaming for users sporting 3900x or 3950x.


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## Fry178 (Dec 20, 2019)

Because then you wont run out of vram, nor do you need more than low end card.


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## ratirt (Dec 20, 2019)

biffzinker said:


> Who is going to pair a midrange RX 5500 4GB card with a X570 mainboard just for PCIe 4.0?


From the market standpoint somebody will. Who ? I don't know because I din't planned or market these products.
Although, if you consider a 3950 or 3900 as a small server or a workstation the 5500 non and XT might be of a value to you in a content creation ballpark?



R0H1T said:


> Aren't they testing the pcie 3.0 runs on 9900k & the 4.0 runs on Ryzen 3xxx if so how is this Apples to apples?
> Depends on what you're doing with it, are you telling me people don't pair a TR (or Intel HEDT) with Nvidia's mid range xx50 cards? This card may simply be used for driving the display & occasional gaming for users sporting 3900x or 3950x.


BTW the 8x PCIe4 has exactly the same bandwidth as 16x PCIe 3.0 The graph doesn't say how many lanes they are actually using. I think this problem is blown out of proportions anyway. It's like creating a problem for a reason than actually looking if there is one.


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## IceShroom (Dec 20, 2019)

ratirt said:


> BTW the 8x PCIe4 has exactly the same bandwidth as 16x PCIe 3.0 The graph doesn't say how many lanes they are actually using. I think this problem is blown out of proportions anyway. It's like creating a problem for a reason than actually looking if there is one.


But Navi14 has 8 PCI-e lane not 16. When you put 5500XT in a PCI-e x16 slot it will only initialize 8 lane cause the card has 8 physical lane.


----------



## biffzinker (Dec 20, 2019)

ratirt said:


> From the market standpoint somebody will. Who ? I don't know because I din't planned or market these products.
> Although, if you consider a 3950 or 3900 as a small server or a workstation the 5500 non and XT might be of a value to you in a content creation ballpark?


My point may of been missed. What I was trying to get at was to avoid a performance hit because of AMD offering a 4 GB on-board RX 5500 option for sharing wiith system RAM via x8 PCIe 4.0 interface who out there is going to bother with PCIe 4.0 when it is likely to be replaced by PCIe 5? The combination of the two didn't make any sense to me just for the specification bump.


----------



## ratirt (Dec 20, 2019)

IceShroom said:


> But Navi14 has 8 PCI-e lane not 16. When you put 5500XT in a PCI-e x16 slot it will only initialize 8 lane cause the card has 8 physical lane.


Well that is an issue but AMD claims it is enough. I think it is enough since still, the issue here is with the VRAM capacity. That is the main problem not the bandwidth. These 4GB cards are basically not for heavy gaming anyway and for what they are for, the 4GB is more than enough.


biffzinker said:


> My point may of been missed. What I was trying to get at was to avoid a performance hit because of AMD offering a 4 GB on-board RX 5500 option for sharing wiith system RAM via x8 PCIe 4.0 interface who out there is going to bother with PCIe 4.0 when it is likely to be replaced by PCIe 5? The combination of the two didn't make any sense to me just for the specification bump.


I wouldn't be so sure about who would bother because PCIe 5 is coming out. Cause when AMD announced that they will support PCIe 4.0 with the upcoming x570 chipset, people started rumbling about, why PCIe4.0 ? PCI 3.0 is enough and besides the 4.0 costs so damn more. Now you say why bother with 4.0 when 5.0 is coming out?
There's already 6.0 announced to be released so why bother with 5.0 anyway?
They will bother with 3.0 and 4.0 because, certain graphics cards may not need so much bandwidth or wont be able to utilize it anyway. Different segments different needs. So why bother going with more expensive 5.0 when 4.0 or even 3.0 will suffice? 5500 is a good example isn't it? It is limited to 8 lanes despite PCIe version and it is enough as long as you keep the VRAM capacity in check for the tasks you want to use that graphics for.
In conclusion I disagree with your statement,"who will bother with PCIe 4.0 when 5.0 is approaching".


----------



## EarthDog (Dec 20, 2019)

R0H1T said:


> Aren't they testing the pcie 3.0 runs on 9900k & the 4.0 runs on Ryzen 3xxx if so how is this Apples to apples?


No. Same system. Just flipped from 3 to 4 in the bios.



IceShroom said:


> But Navi14 has 8 PCI-e lane not 16. When you put 5500XT in a PCI-e x16 slot it will only initialize 8 lane cause the card has 8 physical lane.


it has x8 electrical. It is a x16 slot, physically. Only 8 lanes are used in the card.


----------



## R0H1T (Dec 20, 2019)

EarthDog said:


> No. Same system. Just flipped from 3 to 4 in the bios.
> 
> it has x8 electrical. It is a x16 slot, physically. Only 8 lanes are used in the card.


Right, how can you explain this then?


----------



## EarthDog (Dec 20, 2019)

R0H1T said:


> Right, how can you explain this then?


What are you actually asking? Explain why that bandwidth doubled? Because pcie 4.0 has 2x the bandwidth over 3.0.


----------



## Kissamies (Dec 20, 2019)

Assimilator said:


> People aren't expecting playable framerates on a 1030. Take your whataboutism elsewhere.


People don't always play on high settings. GT 1030 runs BF1 1080p low very well for example.

Haven't actually tested does that PCIE2.0 x4 bottleneck a GT 1030 how much..


----------



## sutyi (Dec 20, 2019)

Assimilator said:


> So AMD's lack of good delta compression finally bites them.



They have DCC since Polaris if I remember correctly, wasn't as effecient as nVIDIAs tho. Probably RDNA had improved uppon that, so don't know if it's a problem to be honest.

Wolfenstein New Colossus on Mein Leben settings satures the 6GB VRAM on my GTX 1060, effectivelly making it an uplayable stutterfest on certain maps and zones. 4GB is just really not enough to drive that game and many newer ones anymore on the highest settings (especially textures) regardless of actual framerates. Heck... there are some games that wont even stream in the highest quality textures regardless the graphics settings if it goes way beyond the actual available videomemory.

I'm sorry to break this to some... but in late 2019 / early 2020, the new dGPUs with 4GB VRAM are the new 2GB cards. I'm even contemplating to not buy a new card with anything less then 8GBs for the next couple of years to come.

On the matter of being bandwith starved on PCIe 3.0 8X... well yes and no. It's more like PCIe 4.0 8X easing the problem somewhat, not really solving the matter of running out of VRAM. You probably wouldn't be playing any sort of shooter game at 30-40fps. At least I wouldn't.

AMD should've slapped on the other 8 PCIe lanes regardless I highly doubt it would've eaten that much die space or PCB.


----------



## arbiter (Dec 21, 2019)

Ok Article that claims x8 3.0 isn't enough for 5500xt is from what can tell a joke. Problem with with everything is running these games are ultra settings will eat 4gb. As even techpowerup tested with a 2080ti which that 5500xt can't hold a candle when you look at avg on TPU here (73.3fps vs 174.4fps, https://www.techpowerup.com/review/gigabyte-radeon-rx-5500-xt-gaming-oc-8-gb/28.html). Seems like who ever wrote the was writing a click bait title to get people to click and i can't read language its writen in to see if what he said was just that click bait or at the end he points out that likely ram limiting issue. For people that report that 5500xt is 8 lane limited which means its 8x pci 3.0 and 4.0 no matter what its on. 3.0 x16 used on 2080ti is same bandwidth as 4.0 8x. Shows that even a card that is 2.5x times faster in avg fps isn't being crippled by 8x pci3.0. Throw on top that the graph on that other article even shows 8gb cards are near performance though 4.0 yes is faster which is normal since less time takes to move the data to the card.

End summary is if you plan to game on ultra settings, DON'T BUY A CARD WITH 4GB MEMORY unless those games are older games that won't ever use 4gb. Any new games you want 8gb memory min or be ready to turn off some settings like AA to start with then work rest from there.


----------



## TheoneandonlyMrK (Dec 21, 2019)

GoldenX said:


> My point is, no one is excused for this crap (well, maybe Intel, for now.). Those GPUs are already dirt cheap to produce, and I bet the savings in PCIe lanes are marginal at best. Sounds more like AMD and Nvidia found a new way to make people look at low/mid end GPUs with more VRAM, by artificially limiting their bandwidth.
> Else, who would get the 8GB version of the 5500?


Lower end Sku's have nearly always got restrained bandwidth.
This is pure bad smell Bs , I could have shown the exact same issues between the 1060 3 and 6 gig GPUs or the 470/580 4-8GB ..

Pick the right load and boom issues.

Our own guy here w1zzard has the pciex at minimal, anyone else who's tried will find down to pciex3x4 quite capable of running a Gpu.

I get point slips if I drop pciex speeds but damn the hackish nonesense in this.


----------



## Fry178 (Dec 21, 2019)

I know pcghw since they started, not a mag/site that does that kind of crap.
They wanted to show that even with the card limited to x8, running it on pcie 4 (vs 3) does help with performance.

That said, having more vram isnt gonna help much on most smaller cards.
Just because i give it 8gb  doesn't mean you will actually have the horsepower to get the fps needed to run the game.

Tho usually running pcie 3 cards at x8, usually gets you a bit better performance (less overhead).
Dont have a ti myself, but all xx70/80 cards i tested, ran better.
Guess ill do some benching this weekend to confirm with pcie 4 (x570 and 2080)..


----------



## arbiter (Dec 22, 2019)

ratirt said:


> Well that is an issue but AMD claims it is enough. I think it is enough since still, the issue here is with the VRAM capacity. That is the main problem not the bandwidth. These 4GB cards are basically not for heavy gaming anyway and for what they are for, the 4GB is more than enough.


If you read the story its easy to see its a vram issue, If 3.0 8x was really a problem then the 8gb 3.0 8x card would show a same kinda loss as well but it doesn't.


----------



## GoldenX (Dec 23, 2019)

PCIe bandwidth IS important on VRAM limited scenarios.
What do you use after VRAM is full? RAM.
Where does the info between RAM and VRAM travel? PCIe.


----------



## Fry178 (Dec 23, 2019)

Nope. you dial down res/settings, or upgrade your card.

And if the card is "new", then ppl didnt do their research and bought the wrong card,
or badly planned upgrade.
its like ppl hitting the key (ignition) to keep a dead car going with the alternator.


----------



## Flaky (Dec 23, 2019)

+1

RAM is VRAM's insurance policy just as pagefile is RAM's insurance policy.
You're supposed to avoid scenarios which cause any of them to be used.


----------



## Xuper (Dec 23, 2019)

gigabyte says : PCI-E 4.0 x 16  , Asrock says : PCI-E 4.0 x 8  









						Radeon™ RX 5500 XT GAMING OC 8G Specification | Graphics Card - GIGABYTE Global
					

Discover AORUS premium graphics cards, ft. WINDFORCE cooling, RGB lighting, PCB protection, and VR friendly features for the best gaming and VR experience!




					www.gigabyte.com
				



asrock.com/Graphics-Card/AMD/Radeon%20RX%205500%20XT%20Phantom%20Gaming%20D%208G%20OC/

so PCIe 3.0 x8 mode only applies to 4GB? or 8GB?


----------



## Flaky (Dec 23, 2019)

@Xuper
5500 is an x8 chip, and nothing can change that.
Gigabyte seems to be unable to decide whether they want to specify physical PCIe (x16) or electrical (4.0).
You even have a review at tom's of this exact card with gpu-z shot included.


----------



## SomeOne99h (Dec 23, 2019)

(*the 4gb only benefits from pcie 4.0. Thanks for clarifying this steve. You can rest now. And merry christmas*)
*Steve's response: *"and probably only if you have at least 16GB's of system memory "


----------



## FordGT90Concept (Dec 23, 2019)

Yeah, PCIe performance only seriously comes in to play when the VRAM is saturated (using more PCIe bandwidth to reach the system RAM).  Don't want problems with modern games? Get a card with 8 GiB of VRAM.  4 GiB is budget now.

I'm running a 5500 XT 8 GiB on PCIe 3.0 and I'm not having any performance issues.


----------



## eidairaman1 (Dec 23, 2019)

FordGT90Concept said:


> Yeah, PCIe performance only seriously comes in to play when the VRAM is saturated (using more PCIe bandwidth to reach the system RAM).  Don't want problems with modern games? Get a card with 8 GiB of VRAM.  4 GiB is budget now.
> 
> I'm running a 5500 XT 8 GiB on PCIe 3.0 and I'm not having any performance issues.



The card is only wired for 8x right or 16x?


----------



## SomeOne99h (Dec 23, 2019)

eidairaman1 said:


> The card is only wired for 8x right or 16x?


8x if I am not mistake.


----------



## EarthDog (Dec 23, 2019)

SomeOne99h said:


> 8x if I am not mistake.


Correct. The whole reason why it is slower once the 4gb VRAM fills up.


----------



## eidairaman1 (Dec 23, 2019)

SomeOne99h said:


> 8x if I am not mistake.



Ok so its a 560/560D


----------



## HTC (Dec 23, 2019)

SomeOne99h said:


> 8x if I am not mistake.



Yes. It benefits from PCIe 4.0 because 8x bandwidth with 4.0 is equal to 16x bandwidth with 3.0.

What surprises me is how this is possible since none of @W1zzard 's tests with PCIe bandwidth thus far (and there have been several) show the kind of differences in performance shown in the OP's link.


----------



## EarthDog (Dec 23, 2019)

HTC said:


> Yes. It benefits from PCIe 4.0 because 8x bandwidth with 4.0 is equal to 16x bandwidth with 3.0.
> 
> What surprises me is how this is possible since none of @W1zzard 's tests with PCIe bandwidth thus far (and there have been several) show the kind of differences in performance shown in the OP's link.


because his testing is with a card that doesnt saturate the available vram nor is it wired for x8.


----------



## HTC (Dec 23, 2019)

EarthDog said:


> because his testing is with a card that doesnt saturate the available vram nor is it wired for x8.


And that suggest he needs to change the way he tests GPU's PCIe bandwidth saturation, no?

Unless i'm grossly misunderstanding this "phenomena" ...


----------



## Fry178 (Dec 23, 2019)

No.
That was only to show this isnt an issue with pcie bandwidth, as it only applies to cards that are vram limited (and swap to ram).


----------



## arbiter (Dec 24, 2019)

HTC said:


> And that suggest he needs to change the way he tests GPU's PCIe bandwidth saturation, no?
> 
> Unless i'm grossly misunderstanding this "phenomena" ...


Nothing wrong with testing used but way the headline was worded is the problem. When you word stories like that its called click bait. I can't read german so maybe in story they note that its vram is limited but if that was the case would said something so kinda tells me they didn't.


----------



## FordGT90Concept (Dec 24, 2019)

HTC said:


> Yes. It benefits from PCIe 4.0 because 8x bandwidth with 4.0 is equal to 16x bandwidth with 3.0.
> 
> What surprises me is how this is possible since none of @W1zzard 's tests with PCIe bandwidth thus far (and there have been several) show the kind of differences in performance shown in the OP's link.


It's only going to rear its head in games that need more than 4 GiB VRAM.  It does show up in W1zzard's testing.

RX 5500 XT 4 GiB (1737/1845/1750) is 9-26% slower than RX 590 8 GiB:








						Sapphire Radeon RX 5500 XT Pulse 4 GB Review
					

Sapphire's factory-overclocked Radeon RX 5500 XT Pulse comes with an amazing cooler that delivers excellent temperatures and unbelievable noise levels at the same time. Idle fan stop and a dual BIOS are included, too, for a very reasonable price increase of $10.




					www.techpowerup.com
				




RX 5500 XT 8 GiB (1737/1845/1750) is 3-4% slower than RX 590 8 GiB.








						MSI Radeon RX 5500 XT Gaming X 8 GB Review
					

The MSI Radeon RX 5500 XT Gaming X features twice the VRAM of the 4 GB OEM model, which we found to make a surprising difference in games, even at 1080p. As expected, the card includes an extremely quiet cooler, idle-fan-stop, and a backplate.




					www.techpowerup.com
				




That's because some of the games in his test do exceed 4 GiB.  It soars to 26% at 4K because they're having to fall back on the system RAM.  He tested using a motherboard that's PCIe 3.0 x16.

The 4 GiB card numbers wouldn't be quite as terrible had he tested with a PCIe 4.0 motherboard but they'll never reach the 8 GiB card unless the games that exceed 4 GiB were purged from the benchmark.  Even so, TechSpot testing shows 8 GiB 3.0 -> 8 GiB 4.0 produces frames about 2 ms quicker in Wolfenstein Youngblood so it seems that Vulkan benefits from faster lanes.


----------



## Fry178 (Dec 24, 2019)

@*arbiter*
I know pcghw since they started, not a mag/site that does that kind of crap.
They wanted to show that even with a card limited to x8, running it on pcie 4 (vs 3.0) does help with performance,
not tha 4.0 wasnt an improvement, and their title was reflecting that (in german).


----------



## (*^^*) (Dec 24, 2019)

Present a PC that can play a light game to the siblings.  Because it is troublesome to buy a new motherboard, I decided to use AMD.  The set of CPU and X570 was cheap and bought.

 By the way, if the 5500XT4GB works like 8GB for Gen4, that's thankful.
 I was worried about buying 5500XT8GB or 5500XT4GB.  I will buy 5500XT4GB.  With the savings.  Cancel DDR4 3600 8GB × 2.  Buy DDR4 3600 16GB × 2!

 Good to hear good things!  ,Thank you!
 Thanks AMD for leaving unexpected options!


----------



## EarthDog (Dec 24, 2019)

(*^^*) said:


> Present a PC that can play a light game to the siblings.  Because it is troublesome to buy a new motherboard, I decided to use AMD.  The set of CPU and X570 was cheap and bought.
> 
> By the way, if the 5500XT4GB works like 8GB for Gen4, that's thankful.
> I was worried about buying 5500XT8GB or 5500XT4GB.  I will buy 5500XT4GB.  With the savings.  Cancel DDR4 3600 8GB × 2.  Buy DDR4 3600 16GB × 2!
> ...


it doesnt work like 8gb... but works better in vram full situations. honestly... I'd get the 8gb card and leave the memory alone... 16gb is enough... and if you need later, get more ram...


----------



## HTC (Dec 24, 2019)

FordGT90Concept said:


> It's only going to rear its head in games that need more than 4 GiB VRAM.  It does show up in W1zzard's testing.
> 
> RX 5500 XT 4 GiB (1737/1845/1750) is 9-26% slower than RX 590 8 GiB:
> 
> ...



I didn't explain myself properly: i meant this kind of PCIe Bandwidth tests:

Also, i was referring to the original PCGamesHardware article where it's demonstrated the difference is quite a bit higher than the one TechSpot found (different methodology, i guess).

If we do the following to a 5700XT card (as per W1zzard's 2080Ti PCI-scaling tests):



> For all our PCI-Express bandwidth testing, *we limit the bus-width by physically blocking the slot wiring for lanes using insulating tape*. The modular design of PCI-Express allows for this. *The motherboard BIOS lets us limit the PCI-Express feature set to that of older generations, too*. We put the card in its various PCI-Express configurations through our entire battery of graphics card benchmarks, all of which are real-world game tests.



Does it also behave the same as a 5500XT card? And what about non-XT versions of both?


----------



## eidairaman1 (Dec 24, 2019)

(*^^*) said:


> Present a PC that can play a light game to the siblings.  Because it is troublesome to buy a new motherboard, I decided to use AMD.  The set of CPU and X570 was cheap and bought.
> 
> By the way, if the 5500XT4GB works like 8GB for Gen4, that's thankful.
> I was worried about buying 5500XT8GB or 5500XT4GB.  I will buy 5500XT4GB.  With the savings.  Cancel DDR4 3600 8GB × 2.  Buy DDR4 3600 16GB × 2!
> ...



I would suggest a RX570 8G.


----------



## HTC (Dec 24, 2019)

(*^^*) said:


> Present a PC that can play a light game to the siblings.  Because it is troublesome to buy a new motherboard, I decided to use AMD.  The set of CPU and X570 was cheap and bought.
> 
> *By the way, if the 5500XT4GB works like 8GB for Gen4, that's thankful.*
> I was worried about buying 5500XT8GB or 5500XT4GB.  I will buy 5500XT4GB.  With the savings.  Cancel DDR4 3600 8GB × 2.  Buy DDR4 3600 16GB × 2!
> ...


It doesn't: suggest you read the original article while paying more attention to it because that's not what it suggests @ all.


----------



## Fry178 (Dec 24, 2019)

@*(*^^*)*
your wasting your money on the wrong thing.
having 6 or 8gb vram is always better than having another 16gb ram, at least for gaming rigs.


----------



## FordGT90Concept (Dec 24, 2019)

HTC said:


> Does it also behave the same as a 5500XT card? And what about non-XT versions of both?


Not sure what you're asking.  5500 XT and 5500 both have fingers for x16 but only up to x8 are physically connected.  AMD likely does that because fewer traces through the PCB means lower cost for AIBs.


----------



## HTC (Dec 24, 2019)

FordGT90Concept said:


> Not sure what you're asking.  5500 XT and 5500 both have fingers for x16 but only up to x8 are physically connected.  AMD likely does that because fewer traces through the PCB means lower cost for AIBs.


Test PCIe scaling the exact same way the 2080Ti PCIe scaling was tested (check 1st and 3rd links of my previous post and compare the methodology).

Are there other cards with x16 but LESS physically connected, other than the 5500(XT) cards, regardless of manufacturer? If there are, those too should be tested.


----------



## FordGT90Concept (Dec 24, 2019)

Yes, AMD has a lot of them that ship with PCIe x8:








						TechPowerUp
					

Graphics card and GPU database with specifications for products launched in recent years. Includes clocks, photos, and technical details.




					www.techpowerup.com


----------



## HTC (Dec 24, 2019)

FordGT90Concept said:


> Yes, AMD has a lot of them that ship with PCIe x8:
> 
> 
> 
> ...


A couple of those should be tested in "an X570 environment" to see if they too behave the same way as 5500XT.

Depending on which slot in the board it's connected to, doesn't the board turn x16 into x8 when certain amount of devices are connected? IIRC, there are even instances where the boards turn x16 into x4.

There are scenarios where x16 capable GPUs are running @ x8 not because of a BIOS selection but because of the amount of devices hooked up to the system. With these in mind, such PCIe scaling tests ought to be performed, no? Isn't that the whole point of PCIe scaling tests to begin with?


----------



## R0H1T (Dec 24, 2019)

Coming back to this, is there no way to change say the PCIe 4.0 x1 signal into PCIe 3.0 x2 on the fly? Would solve most if not all of these PCIe lane issues on high end boards & cards.


----------



## EarthDog (Dec 24, 2019)

HTC said:


> A couple of those should be tested in "an X570 environment" to see if they too behave the same way as 5500XT.
> 
> Depending on which slot in the board it's connected to, doesn't the board turn x16 into x8 when certain amount of devices are connected? IIRC, there are even instances where the boards turn x16 into x4.
> 
> There are scenarios where x16 capable GPUs are running @ x8 not because of a BIOS selection but because of the amount of devices hooked up to the system. With these in mind, such PCIe scaling tests ought to be performed, no? Isn't that the whole point of PCIe scaling tests to begin with?


Some boards drop to x8 in the GPU slot, yes. But why the reindeer games when simply changing it in the bios for testing is possible.....just like the testing did.

I dont think saturating the pcie bus by playing a game and say transferring a massive file between m.2 nvme drives is really common or worth it? Did I misunderstand?


R0H1T said:


> Coming back to this, is there no way to change say the PCIe 4.0 x1 signal into PCIe 3.0 x2 on the fly? Would solve most if not all of these PCIe lane issues on high end boards & cards.


To what end? Are you talking on a 4.0 x1 slot??? What does that have to do with a gpu?


----------



## HTC (Dec 24, 2019)

EarthDog said:


> Some boards drop to x8 in the GPU slot, yes. But why the reindeer games when simply changing it in the bios for testing is possible.....*just like the testing did.*
> 
> To what end? Are you talking on a 4.0 x1 slot??? What does that have to do with a gpu?


Except it didn't: check the methodology in the 1st and 3rd links in post #95.

It was done with the 2080Ti but not the same way with the 5700XT.

Question: would a regular x16 capable card work @ x8 (in bandwidth) in a PCIe 4.0 x4 slot (due to amount of connected devices) or @ x4?


----------



## EarthDog (Dec 24, 2019)

HTC said:


> Except it didn't: check the methodology in the 1st and 3rd links in post #95.
> 
> It was done with the 2080Ti but not the same way with the 5700XT.
> 
> Question: would a regular x16 capable card work @ x8 (in bandwidth) in a PCIe 4.0 x4 slot (due to amount of connected devices) or @ x4?


I was talking about the original testing in the thread. My fault...

As far as your question, if the x16 physical is at x4 electrical, it should work if it is an amd card. Iirc, nvidia cards dont work under x8.... at least with sli.


----------



## R0H1T (Dec 24, 2019)

EarthDog said:


> To what end? Are you talking on a 4.0 x1 slot??? What does that have to do with a gpu?


No I'm talking about (electrically) converting PCIe 4.0 signal into 2x their equivalent PCIe 3.0 lanes on the fly, for instance on motherboards where the second (GPU) slot is limited to x8 or x4 as the first slot is occupied & this could be useful there. It would also be mightily handy especially for M.2 slots & other (expansion) cards, assuming it can be done in the first place.


----------



## Fry178 (Dec 24, 2019)

there is no difference.
doing it with the board reducing the speed because you have another 2 devices, will be no different then switching bios to lower speed and/or gen.
but even if you switch on purpose to x4 (or because of multiple devices) wont matter much except for ppl owning a 2080ti or faster chip (quadro etc).
those are the only times were i can saturate 3.0 @x8/4.0 @x4.

slower cards will most of the time perform better (pcie 3.0 x8 vs x16) as you have less overhead, should be same with 4.0 @x4.

After using 3DMark11 (X setting) as bench to get some numbers, seems that with pcie 4.0 it won't matter much anymore compared to 3.0 (switching from x16 to x8),
as i get virtually identical numbers no matter what i used (3.0 @8/16 or 4.0 @x8/16), e.g below 0.1% variance (14171 vs 14183).


----------



## IceShroom (Dec 24, 2019)

eidairaman1 said:


> Ok so its a 560/560D


Baffin/Polaris11/Polaris21 has 8 PCI-e lane just like the Navi14.



HTC said:


> A couple of those should be tested in "an X570 environment" to see if they too behave the same way as 5500XT.
> 
> Depending on which slot in the board it's connected to, doesn't the board turn x16 into x8 when certain amount of devices are connected? IIRC, there are even instances where the boards turn x16 into x4.
> 
> There are scenarios where x16 capable GPUs are running @ x8 not because of a BIOS selection but because of the amount of devices hooked up to the system. With these in mind, such PCIe scaling tests ought to be performed, no? Isn't that the whole point of PCIe scaling tests to begin with?


Well those card will be Shader limit before memory limit.


----------



## EarthDog (Dec 24, 2019)

IceShroom said:


> Well those card will be Shader limit before memory limit.


What does this mean? If you run out of memory bad things will happen period. Makes low fps lower.


----------



## IceShroom (Dec 24, 2019)

EarthDog said:


> What does this mean? If you run out of memory bad things will happen period. Makes low fps lower.


I mean those(except 5500XT) card will not have the power to process the texture that requers more than 4GB memory.


----------



## Fry178 (Dec 24, 2019)

That would also depend on the game.
I can play something from 10y ago (wont cost much fps wise), but still use higher res like 1080p/1440p or even 4K, which requires more vram.


----------



## EarthDog (Dec 24, 2019)

IceShroom said:


> I mean those(except 5500XT) card will not have the power to process the texture that requers more than 4GB memory.


It would just be slower, as I said.


----------



## Flaky (Dec 25, 2019)

HTC said:


> Question: would a regular x16 capable card work @ x8 (in bandwidth) in a PCIe 4.0 x4 slot (due to amount of connected devices) or @ x4?


I totally don't get the "(in bandwidth)" part in question.

Slot has 4 lanes -> the resulting connection cannot have more than 4 lanes.



R0H1T said:


> No I'm talking about (electrically) converting PCIe 4.0 signal into 2x their equivalent PCIe 3.0 lanes on the fly (...)


I don't recall any hardware (at least in consumer segment) capable of changing lane widths after the POST is done.
Doing such thing may require the PCIe controller to reinitialize - that would mean that all the devices connected to it would have to be disabled and temporairly soft-disconnected.
Let's not forget that reallocationg lanes somewhere else would require physically re-routing the traces - and that is a hardware cost.


----------



## Vya Domus (Dec 25, 2019)

GoldenX said:


> PCIe bandwidth IS important on VRAM limited scenarios.



Funny how literally no one had a clue about any of this up until a week ago but now it has become very important ? No, it hasn't really, it's a monumental waste of time to worry about PCIe bandwidth, the VRAM is what matters.



GoldenX said:


> What do you use after VRAM is full? RAM.



This is improper, GPUs never use system RAM, it's simply too slow, we aren't talking a few FPS lost here and there, no, frames would take seconds to be processed.

The games simply swap memory in and out of the card's memory, it never gets directly accessed from across the PCIe lanes.


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## EarthDog (Dec 25, 2019)

Vya Domus said:


> Funny how literally no one had a clue about any of this up until a week ago but now it has become very important ? No, it hasn't really, it's a monumental waste of time to worry about PCIe bandwidth, the VRAM is what matters.
> 
> 
> 
> ...


of course vram is the primary issue. But we've seen testing that shows in vram limited situations the bus helps. If the data was transferring internally and not using pcie and ram, we wouldnt see these performance increases in vram limited situations.

If it isnt using system ram and the pcie bus in some capacity, why does the testing show notable increases when using the bus with more bandwidth (where it didnt before even with a 5700 xt)?

It's also worth noting that integrated gpus use system ram and AMD's does a decent job at 1080p gaming with it.


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## cucker tarlson (Dec 25, 2019)

GoldenX said:


> Inb4 people forgets the GT1030 suffers the same problem.


1030 is a turd for gaming.
it's a good multi monitor card though,and for that the pci-lanes don't matter,


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## GoldenX (Dec 25, 2019)

Vya Domus said:


> Funny how literally no one had a clue about any of this up until a week ago but now it has become very important ? No, it hasn't really, it's a monumental waste of time to worry about PCIe bandwidth, the VRAM is what matters.
> 
> 
> 
> ...


Chech what the shared GPU RAM is, you can look at it from the task manager or GPU-Z. Any GPU uses system RAM as if it were an IGP, as a swap. Always.
Users didn't know it, doesn't make it a lie, specially with provided evidence.


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## cucker tarlson (Dec 25, 2019)

I would not like to get a $170 card and find out it's massively limited at 1080p while a $160 1650 super does just fine.
Not only is this card super late and badly priced,it's gonna give you unplayable experience at 1080p now,let alone in the future.
Like I was saying,*there should be one 5500xt with 192-bit 6gb memory at $180* and it'd be a very strong contender to the lower Super lineup,but AMD proved themselves incompetent again.And that's not even touching their driver issues.


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## Vya Domus (Dec 25, 2019)

GoldenX said:


> Any GPU uses system RAM as if it were an IGP, as a swap. Always.



That memory is for swapping contents of the GPU. There is no lie, you cannot access memory contents of GPUs without transferring the data first, it's simply not possible. No API allows for this, you can't get something like a pointer to VRAM memory from the host side of things (CPU and RAM). Be it a DirectX shader or a CUDA compute kernel they all operate on buffers that have been transferred first into memory and never accessed across the system bus. That would be unimaginably slow.

Say you need to go through 1 GB of data 1000 times, you have two options : get that memory first into VRAM and access it 1000 times at VRAM latency or access it 1000 times at several times the magnitude of VRAM latency across the PCIe connection from system memory. Which option do you think it's faster ?



GoldenX said:


> Any GPU uses system RAM as if it were an IGP, as a swap. Always.



Definitely not always, only when it's needed.



EarthDog said:


> If it isnt using system ram and the pcie bus in some capacity



It's using RAM in the sense that that's where all the buffers are kept, the buffers however are never accessed directly by the GPU, they have to be in it's VRAM before that's possible.



EarthDog said:


> (where it didnt before even with a 5700 xt)?



The 5700XT has more memory and it also has more PCIe lanes. Everything else works in the same way.


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## HTC (Dec 25, 2019)

Flaky said:


> *I totally don't get the "(in bandwidth)" part in question.
> 
> Slot has 4 lanes -> the resulting connection cannot have more than 4 lanes.*
> 
> ...


This was true with up to PCIe 3.0, but what about with PCIe 4.0 slots? Does a x4 card (electrically and or / for whatever other reason functioning @ x4) work @ x4 or @ x8 in a PCIe 4.0 slot?

This whole issue stems from the fact that x8 is working as x16 in a PCIe 4.0 slot: does the same apply to x4?


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## FordGT90Concept (Dec 25, 2019)

cucker tarlson said:


> I would not like to get a $170 card and find out it's massively limited at 1080p while a $160 1650 super does just fine.
> Not only is this card super late and badly priced,it's gonna give you unplayable experience at 1080p now,let alone in the future.
> Like I was saying,*there should be one 5500xt with 192-bit 6gb memory at $180* and it'd be a very strong contender to the lower Super lineup,but AMD proved themselves incompetent again.And that's not even touching their driver issues.


*cough* 8 GiB





The question is thus: Why do GeForce cards perform so much better with 4 GiB compared to AMD cards?  Maybe it is because of x16 versus x8 (faster RAM access).


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## cucker tarlson (Dec 25, 2019)

FordGT90Concept said:


> *cough* 8 GiB


5500xt 8gb sells at 1660 super price


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## FordGT90Concept (Dec 25, 2019)

Because AMD is letting AIBs clear inventory of older stock (especially RX 590, RX 580, and RX 570).  The 5500 cards (all of them) will come down in price after they're done.


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## GoldenX (Dec 25, 2019)

Vya Domus said:


> That memory is for swapping contents of the GPU. There is no lie, you cannot access memory contents of GPUs without transferring the data first, it's simply not possible. No API allows for this, you can't get something like a pointer to VRAM memory from the host side of things (CPU and RAM). Be it a DirectX shader or a CUDA compute kernel they all operate on buffers that have been transferred first into memory and never accessed across the system bus. That would be unimaginably slow.
> 
> Say you need to go through 1 GB of data 1000 times, you have two options : get that memory first into VRAM and access it 1000 times at VRAM latency or access it 1000 times at several times the magnitude of VRAM latency across the PCIe connection from system memory. Which option do you think it's faster ?
> 
> ...


You just confirmed it yourself, after VRAM is full, PCIe is the next bottleneck.


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## cucker tarlson (Dec 25, 2019)

FordGT90Concept said:


> Because AMD is letting AIBs clear inventory of older stock (especially RX 590, RX 580, and RX 570).  The 5500 cards (all of them) will come down in price after they're done.


so amd still wants to sell 2.5 year old polaris 10 months after 16-series came out and will continue to mark up their new gen cards until the inventory is gone
this sounds like they're not doing consumers in this segment much favor

let me guess,they'll throw rx590s with 10-game bundles at ampere cards


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## Vya Domus (Dec 25, 2019)

GoldenX said:


> You just confirmed it yourself, after VRAM is full, PCIe is the next bottleneck.



Only thing I confirmed is the fact that GPUs don't use system RAM, ever, they only use what's in the VRAM. After the VRAM is full, you can forget about it, PCIe 4.0 or 3.0 or x8 or whatever, it's over, performance will tank.

The situation where you're running out of memory it's a game over scenario in any software of any kind, only thing you can do is ensure it doesn't crash right away. If you can.


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## GoldenX (Dec 25, 2019)

Memory heaps are used to have quicker stream of RAM<>VRAM, on a driver level. So RAM is used, but never directly.


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## Vya Domus (Dec 25, 2019)

GoldenX said:


> So RAM is used, but never directly.



The GPU fetches instructions and data from it's own memory, all the time, never from system memory. It never uses RAM, directly or indirectly via DMA, I don't know how I could make this any simpler, I have to give up I guess.

Nvidia does have something like that which is reserved for Teslas with CUDA I think, I don't know if anything commercial uses it or if it requires something else to work.


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## (*^^*) (Dec 25, 2019)

FordGT90Concept said:


> *cough* 8 GiB
> 
> 
> 
> ...



In the first place, people who play Assassin's Creed in the 1660 and 5500 series.  not many.  Most people who need 1660 or 5500XT play lighter games.  In the first place, there is no problem even if 5500XT4GB is slightly inferior to 16604GB.  Rather, the game structure is optimized for NVIDIA.  It can be considered that a little difference is good.  Do you express this as failure?  Anyway, we have 5600XT.  For light gamers who are not interested in being fast, the 5500XT and Gen4 phenomena may be a good thing.


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## cucker tarlson (Dec 25, 2019)

(*^^*) said:


> In the first place, people who play Assassin's Creed in the 1660 and 5500 series.  not many.  Most people who need 1660 or 5500XT play lighter games.


absolutely bs



(*^^*) said:


> For light gamers who are not interested in being fast, the 5500XT and Gen4 phenomena may be a good thing.


yes,cause why have your budget card run games without a board that costs more than the card.brilliant.


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## GoldenX (Dec 25, 2019)

(*^^*) said:


> In the first place, people who play Assassin's Creed in the 1660 and 5500 series.  not many.  Most people who need 1660 or 5500XT play lighter games.  In the first place, there is no problem even if 5500XT4GB is slightly inferior to 16604GB.  Rather, the game structure is optimized for NVIDIA.  It can be considered that a little difference is good.  Do you express this as failure?  Anyway, we have 5600XT.  For light gamers who are not interested in being fast, the 5500XT and Gen4 phenomena may be a good thing.


What kind of logic is that?



Vya Domus said:


> The GPU fetches instructions and data from it's own memory, all the time, never from system memory. It never uses RAM, directly or indirectly via DMA, I don't know how I could make this any simpler, I have to give up I guess.
> 
> Nvidia does have something like that which is reserved for Teslas with CUDA I think, I don't know if anything commercial uses it or if it requires something else to work.








						AMD Radeon R9 200 Series - Vulkan Hardware Database by Sascha Willems
					






					vulkan.gpuinfo.org
				






That's my 270x, you can have access to some "fast driver level 256MB", the rest of the 2GB, and some "additional" 8GB of RAM. All that "VRAM" is available to developers.
Check other cards, you will see similar stuff. The RAM heap will vary in size according to what the PC has.


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## EarthDog (Dec 25, 2019)

Vya Domus said:


> It's using RAM in the sense that that's where all the buffers are kept, the buffers however are never accessed directly by the GPU, they have to be in it's VRAM before that's possible.


.....which it uses the pcie bus to send from ram to the card.


Vya Domus said:


> The 5700XT has more memory and it also has more PCIe lanes. Everything else works in the same way.


Right... just showing that overall performance doesnt matter from 4.0 x16 to 3.0 x16 when vram isnt filled. Here we have vram being filled and the pcie bus is used to swap that data and it's faster. If it isnt the pcie bus... the only variable that changed... what is it?



Vya Domus said:


> The games simply swap memory in and out of the card's memory, it never gets directly accessed from across the PCIe lanes.


correct. But that data swaps from system ram back to vram over the pcie bus to be read. If it is frequently accessed and swapped, makes sense what we are seeing...what the tests show.



FordGT90Concept said:


> The question is thus: Why do GeForce cards perform so much better with 4 GiB compared to AMD cards? Maybe it is because of x16 versus x8 (faster RAM access).


..this and it's better memory compression algos too.


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## GoldenX (Dec 25, 2019)

Just look at the task manager while you play a game. You always use a portion of RAM for the GPU (and it's not only for textures). Thing is, if VRAM is not filled, you never see the performance drop.
Now, if you have a low amount of VRAM, it reaches 100%, you PCIe bus is slower due to "cost reducing electrical limitations", and to make it worse, you use DDR4 2400MHz RAM, or worse, DDR3... The low end users just got one hell of a punch to the guts.


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## Vya Domus (Dec 25, 2019)

GoldenX said:


> That's my 270x, you can have access to some "fast driver level 256MB", the rest of the 2GB, and some "additional" 8GB of RAM. All that "VRAM" is available to developers.
> Check other cards, you will see similar stuff. The RAM heap will vary in size according to what the PC has.



How does any of this prove the GPU can fetch and execute stuff directly from RAM without having to make copies first to their local memory ?

You do realize these are still associated with local and host memory right ? That's why they're distinct regions in the first place, they are not all VRAM.

See that DEVICE_LOCAL_BIT on the 2 GB region that doesn't exist for the 8 GB one ? Local means GPU visible only memory, that's why the heap associated with the system memory doesn't have that flag

... because it isn't VRAM ...



GoldenX said:


> View attachment 140402
> Just look at the task manager while you play a game. You always use a portion of RAM for the GPU (and it's not only for textures). Thing is, if VRAM is not filled, you never see the performance drop.
> Now, if you have a low amount of VRAM, it reaches 100%, you PCIe bus is slower due to "cost reducing electrical limitations", and to make it worse, you use DDR4 2400MHz RAM, or worse, DDR3... The low end users just got one hell of a punch to the guts.



You can show me this all day, unless you can prove that shared memory is accessed directly be the GPU, which it can't do, you're wasting your time. At one point you'll need to realize that not all memory that gets managed by the API actually ends up on the GPU.


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## GoldenX (Dec 25, 2019)

It's managed by the driver (or in Vulkan's case, the developer), and it doesn't change the fact that PCIe and RAM performance is needed when you fill your VRAM.


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## Vya Domus (Dec 25, 2019)

GoldenX said:


> It's managed by the driver



Exactly but those copies still need to be made, they're just not exposed to the programmer.


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## Flaky (Dec 25, 2019)

HTC said:


> This was true with up to PCIe 3.0, but what about with PCIe 4.0 slots?


Nothing has changed in regard to how lane count and pcie generation is negotiated, and affects resulting link and it's bandwidth.



HTC said:


> Does a x4 card (electrically and or / for whatever other reason functioning @ x4) work @ x4 or @ x8 in a PCIe 4.0 slot?
> 
> *This whole issue stems from the fact that x8 is working as x16 in a PCIe 4.0 slot*: does the same apply to x4?


This is confusing and nonsense at the same time. Lane count is the number of active physical, electrical transmit+receive pairs between the controller and the device.
If some diagnostic program reports wider link than a certain port or device supports, it simply got it wrong.

The whole "as if"/"is working as" simplification causes more confusion than it is worth. This stuff is really simple.
PCIe gen + PCIe lane count *=>* resulting bandwidth
*Not the other way around.*


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## HTC (Dec 26, 2019)

Flaky said:


> Nothing has changed in regard to how lane count and pcie generation is negotiated, and affects resulting link and it's bandwidth.
> 
> 
> This is confusing and nonsense at the same time. Lane count is the number of active physical, electrical transmit+receive pairs between the controller and the device.
> ...



There's obviously some confusion here and i don't know if it's from you, me or both.

Take a look @ these two pics (from the article in the OP):



 



These pics show the EXACT SAME CARD: once in a PCIe 3.0 board and the another in a PCIe 4.0 board. As can be seen, the one in a PCIe 4.0 board has nearly double the bandwidth in GPU read / write and this is supposed to be BECAUSE the x8 PCIe 3.0 card is actually working as x16 PCIe 3.0 *in an X570 board*, which is why the bandwidth nearly doubles, EVEN thought it only is x8 electrically.

My question was: does an x4 PCIe 3.0 card behave the same way?

If it does, is this by accident from the board dudes or something in the drivers that enables this? Perhaps a combination of both? Or is it supposed to be working as intended?

EDIT

Strange: it's supposed to be the same card but there are slight differences, such as 20MHz speed difference, among others.


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## Flaky (Dec 26, 2019)

HTC said:


> (...) BECAUSE the x8 PCIe 3.0 card is actually working as *x16* PCIe 3.0 *in an X570 board*, which is why the bandwidth nearly doubles, EVEN thought it only is x8 electrically.


Just stop.
On the left you have PCIe 3.0 x8 connection.
On the right you have PCIe 4.0 x8 connection.
That's it, and that's all. There is no x16 anywhere here.


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## HTC (Dec 26, 2019)

Flaky said:


> Just stop.
> On the left you have PCIe 3.0 x8 connection.
> On the right you have PCIe 4.0 x8 connection.
> That's it, and that's all. There is no x16 anywhere here.



It seems i'm expressing myself wrong: they *BOTH* use x8 connection but one has x8 speed while the other has THE EQUIVALENT of x16 speed.

EDIT

It's as if the *BOARD'S PCIe 4.0 slot* is doubling the card's PCIe 3.0 connection speed. It's not supposed to do that, *I THINK*, but it appears that's what's happening with the 5500XT. Dunno how else to explain that read / write GPU memory speed doubling.

EDIT  #2

Wait.

I think i got it backwards: it's not the X570 board that doubles the speed but ALL other NON-PCIe 4.0 capable boards that LIMIT the x8 PCIe 4.0 to PCIe 3.0, thus HALVING the speed. This actually makes a lot more sense.


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## Fry178 (Dec 26, 2019)

well, because 3.0 is slower, not because its "limiting" it.
See it like sata. 3 is faster than 2 with the same amount of connections.

Everytime you go "up" one generation, it doubles the bandwidth each lane can carry, nothing more.

ppl *might say* "4.0 x8 has the *same speed* (as 3.0 x16)", but thats only true in regards to performance, not physical/electrical lanes.


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## HTC (Dec 26, 2019)

Fry178 said:


> well, because 3.0 is slower, not because its "limiting" it.
> See it like sata. 3 is faster than 2 with the same amount of connections.
> 
> Everytime you go "up" one generation, it doubles the bandwidth each lane can carry, nothing more.
> ...



That was my point exactly.

I think i figured it out though, like i said in the 2nd edit of my previous post.

It's not the X570 board that is doubling the speed but, instead, *ALL the boards that are NOT capable of PCIe 4.0 are HALVING the bandwidth speed of the PCIe capable 4.0 cards.*

With the 5500XT being a PCIe 4.0 capable card, it runs @ double the speed of PCIe 3.0 *so long as the board it's placed in is ALSO PCIe 4.0 capable*. If not, it will run @ PCIe 3.0 speed instead, effectively cutting it's bandwidth speed in half.

This being the case, my earlier question is already answered: a PCIe 4.0 card will run in an X570 board with *twice the bandwidth* VS the exact same card in a PCIe 3.0 board.


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## hat (Dec 26, 2019)

Yeah, that's how PCI-E works. Every generation doubles the bandwidth, so a PCI-E 4.0 card in a 3.0 slot will only have half the bandwidth available to it. This usually isn't a big deal, but when you put a small amount of vram on a card that's wired for 4.0 x8 and stick it in a 3.0 slot (where it will run, of course, at 3.0 x8), you run into serious limitations when the vram runs out. Sending data back and forth between the card and system ram over PCI-E, even if it's 4.0 x16, is going to be a lot slower than just having everything on the card ready to go.


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## GoldenX (Dec 26, 2019)

As simple as that.


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