# PCI-E 8X vs 16X performance difference on Single Card Solution



## suraswami (May 8, 2008)

I checked few reviews and the difference between 8x lane and 16x lane PCI-E is very minimal.  like 3%.  Frys has sale on XFX 8800GT 512MB Alpha Dog version for $150 AR.  If I put it in my Jetway mobo (in my signature) which only has 8x pci-e lane will I loose lots of FPS?

I will end up buying a ATX mobo later.  But its tempting now.  Should I go 3870 instead of 8800GT?


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## Disparia (May 8, 2008)

I wouldn't worry, and besides that model of Jetway says that it was a PCIe x16 @ x16 slot.


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## hat (May 8, 2008)

It depends on the card. If you have a beast of a card like a 9800GX2 or a 3870x2, your performance will be affected. An 8800gt however, minimal difference.


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## suraswami (May 8, 2008)

Jizzler said:


> I wouldn't worry, and besides that model of Jetway says that it was a PCIe x16 @ x16 slot.



It says X16 slot.  But the connection is only 8X because of the chipset 6100-405.


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## hat (May 8, 2008)

Like I said it wouldn't affect performance too much. If you're that worried about it, go ahead and overclock your PCI-E bus, but I don't reccomend going over 120.


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## suraswami (May 8, 2008)

hat said:


> It depends on the card. If you have a beast of a card like a 9800GX2 or a 3870x2, your performance will be affected. An 8800gt however, minimal difference.



hmm I have seen the 8800GT beat the 3870 X2 on some benchies.  If the 88 will not be affected much then I am all set.

Too bad I have to ditch ATI.  3870 (not the X2) is any good?


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## hat (May 8, 2008)

Probably when the 3870 was in its infancy (crappy drivers rushed out of the door)

The 8800GT is slightly faster than a 3870, I can't imagine it being faster than effectively two of them


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## FatForester (May 8, 2008)

I wouldn't worry about it because the real bottleneck is your X2 3800+. Go for it though, because the 8800GT is an awesome card!


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## suraswami (May 8, 2008)

oh sorry.  I am going to put it in the Jetway + X2 5600 machine.


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## suraswami (May 8, 2008)

hat said:


> Probably when the 3870 was in its infancy (crappy drivers rushed out of the door)
> 
> The 8800GT is slightly faster than a 3870, I can't imagine it being faster than effectively two of them



If that is the case then I might get 3870 and still be AMD/ATI fanboy


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## suraswami (May 8, 2008)

not bad my favorite brand is in the same price range.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161218


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## suraswami (May 8, 2008)

this one too has good reviews
http://www.newegg.com/Product/Product.aspx?Item=N82E16814103050


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## hat (May 8, 2008)

What? You don't like HIS? Why?


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## FatForester (May 8, 2008)

suraswami said:


> oh sorry.  I am going to put it in the Jetway + X2 5600 machine.



Oh, ok I see. As far as comparing a 3870 vs. a 8800GT, the 8800GT is faster, it just depends on how much you want to spend. If your mobo is limited by the 8x, then definitely go with the 3870. When PCIe came out years ago, there wasn't a bit of difference between bandwidth speeds.. but now things have changed. If you don't see yourself upgrading in the future, or if the board is indeed only 8x, get the 3870. Otherwise, the 8800GT would be the better choice.


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## suraswami (May 8, 2008)

hat said:


> What? You don't like HIS? Why?



No.  I said my favorite brand is HIS


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## suraswami (May 8, 2008)

FatForester said:


> Oh, ok I see. As far as comparing a 3870 vs. a 8800GT, the 8800GT is faster, it just depends on how much you want to spend. If your mobo is limited by the 8x, then definitely go with the 3870. When PCIe came out years ago, there wasn't a bit of difference between bandwidth speeds.. but now things have changed. If you don't see yourself upgrading in the future, or if the board is indeed only 8x, get the 3870. Otherwise, the 8800GT would be the better choice.



This board I bought because I killed an ECS board.  This is just stop gap before I finally go Phenom.  But my 5600 OCed to 6400 speeds is more than enough in today's new games.  That is reason I thought about investing on a VC.


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## Nyte (Jul 3, 2008)

You should be careful with putting it in the x8 slot...  It's not the bandwidth that's the concern.

Basically, each slot on a motherboard is routed either through the NORTHBRIDGE or the SOUTHBRIDGE.  If it's routed directly through the NORTHBRIDGE, that's fine.  

However, if it's routed through the SOUTHBRDIGE, it will get additionally routed to the NORTHBRIDGE.  That's 2 latency paths for your data which drops performance.  Usually slots that are less than x16 are routed through the SOUTHBRIDGE to NORTHBRIDGE (especially the x1 slots).  The best thing to check is look at your motherboard and track the PCB traces to see if it goes to the NORTHBRIDGE.


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## wolf (Jul 3, 2008)

i run a 9600GT on pci-e 4x and she still gets about 90% of her 16x score.


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## MKmods (Jul 3, 2008)

the mobo is a full X16
Quote:
"PCI Express x16 Slot @ 16-LANE Bandwidth for PCI Express Interface VGA Cards
Designed to run with the next-generation PCI Express bus architecture; the motherboard offers 1 PCI Express x16 slot with 16 lanes bandwidth to support PCI-Express interface compatible add-in cards."

I know when I run my 9600GTs on my SLI mobo (X8 when using SLI) there is practically no loss. The bridge makes up for a bit too.

I would get a 8800 or 9600GT since the chipset is Nvidia.(dont overlook the 8800GS either)


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## Hayder_Master (Jul 3, 2008)

hat said:


> Like I said it wouldn't affect performance too much. If you're that worried about it, go ahead and overclock your PCI-E bus, but I don't reccomend going over 120.



i have also 8800gt pci-e 2.0 16x run on my a bit mobo which is run at 8x , it run well but am try to overclock it
hey guys i need your advice in my thread about overclock 

http://forums.techpowerup.com/showthread.php?p=867373&posted=1#post867373


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## TomBrooklyn (Sep 12, 2010)

I understand a 16x board is going to revert to 8x if SATA 3 or USB3 is employed on a P55 Motherboard.      How much of a video performance hit is going to occur in that case?


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## Wile E (Sep 12, 2010)

TomBrooklyn said:


> I understand a 16x board is going to revert to 8x if SATA 3 or USB3 is employed on a P55 Motherboard.      How much of a video performance hit is going to occur in that case?



In most cases, it shouldn't go down to 8X, but, for the sake of argument, lets assume it does.

The answer is, it shouldn't make much of a difference with all but the highest end cards.


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## Kantastic (Sep 12, 2010)

TomBrooklyn said:


> I understand a 16x board is going to revert to 8x if SATA 3 or USB3 is employed on a P55 Motherboard.      How much of a video performance hit is going to occur in that case?



A few percent or more depending on your GPU... which would be wise to provide.

/Nice necrobump. 



Wile E said:


> In most cases, it shouldn't go down to 8X, but, for the sake of argument, lets assume it does.
> 
> The answer is, it shouldn't make much of a difference with all but the highest end cards.



Some motherboards do for some odd reason, probably not enough bandwidth.


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## TheMailMan78 (Sep 12, 2010)

Sounds like you need a VGA Switch Card in there. Mine runs at 8x also without a "slave".


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