i7-5775C: why did Intel abandon development of eDRAM?

[AusWolf]

Tbh, I'd like to have two identical motherboards, one with 4790k, and the other with 5775c. Overclocking both and comparing them across multitude of workloads would be so fun.

I'd love to test that Iris IGP, too! Or to be fair, even just owning something so rare and unique would be awesome.

 

[Arrakis9]

I actually have one of these chips hanging on display as a wall thropy. IIRC the chip still works but the board died. Would be interesting to see if it still works, the biggest problem I remember with it was the really choppy bios support and having to slipstream updated code into a bios file and force flashing it to my board.

 

[Ayhamb99]

L4 Cache might be making a return with Meteor Lake, which might utilise the same kind of eDRAM.

https://www.phoronix.com/news/Linux-Patch-Intel-MTL-L4-Cache

 

[LabRat 891]

L4 Cache might be making a return with Meteor Lake, which might utilise the same kind of eDRAM.

https://www.phoronix.com/news/Linux-Patch-Intel-MTL-L4-Cache

View attachment 297695

I'm curious as to the 'marketing angle' Intel will play against 3DVcache?

 

[Ayhamb99]

I'm curious as to the 'marketing angle' Intel will play against 3DVcache?

Probably going to be the same marketing strategy that AMD did with their X3D chips against the 13900K

Although i am very curious about how this is going to perform if they release a special sku with L4 Cache

 

[AnotherReader]

So only in the two IBM z15 chips the eDRAM is actually embedded. That is, made on the same die, with the same technology, as the cores and other logic. The chip sizes are extreme here, 700 mm2 for the chip with processor cores.

You're right about the distinction; IBM simply has a longer history of working with eDRAM. POWER7 was IBM's first chip to use eDRAM: 3 years before Intel's first attempt. IBM's eDRAM is different from Intel's. Real World Technologies covered this about a month before the launch of Haswell:

Intel uses a trench capacitor to store the actual data bits. Unlike IBM’s work where the trench is dug into the silicon substrate, Intel’s eDRAM forms a high aspect ratio trench above the transistors in the metal interconnects and interlayer dielectrics and filled with a metal-insulator-metal capacitor.

 

[Nordic]

L4 Cache might be making a return with Meteor Lake, which might utilise the same kind of eDRAM.

https://www.phoronix.com/news/Linux-Patch-Intel-MTL-L4-Cache

View attachment 297695

If they use edram it won't be as good as AMD's cache but the overall package might performance better regardless

 

[AusWolf]

Probably going to be the same marketing strategy that AMD did with their X3D chips against the 13900K

Although i am very curious about how this is going to perform if they release a special sku with L4 Cache

They can try to market it the same way, but it won't be the same. AMD's 3D cache is just an extended L3 cache, while L4 suggests an entirely separate section of cache with a higher latency.

 

[Mussels]

L4 Cache might be making a return with Meteor Lake, which might utilise the same kind of eDRAM.

https://www.phoronix.com/news/Linux-Patch-Intel-MTL-L4-Cache

View attachment 297695

Because AMD had great success in the enterprise/server world with the 3D cache Epyc chips, Intel had to research their own modern variant too

As stated above, bigger L3 and L4 arent the same thing - that's not to say it cant work out and work well, it's just going to be different.
L4 is going to be slower since it's a step higher up the chain, but that also gives it potential to be larger, cheaper and cooler running.

They may leverage some of the tech 3D Xpoint used in the original Optane - it was intended to be used in a caching purpose, so if nothing else some of their internal knowledge, research and patents may apply

 

[Wirko]

They may leverage some of the tech 3D Xpoint used in the original Optane - it was intended to be used in a caching purpose, so if nothing else some of their internal knowledge, research and patents may apply

Now (now?) Intel has Sapphire Rapids with HBM, and that HBM can be one of three things: extension to RAM, the only RAM in the system, or cache.
That's probably intended for customers who order processors literally by the metric ton, so they won't have a retail price tag.

 

[AnotherReader]

Now (now?) Intel has Sapphire Rapids with HBM, and that HBM can be one of three things: extension to RAM, the only RAM in the system, or cache.
That's probably intended for customers who order processors literally by the metric ton, so they won't have a retail price tag.

HBM will be useful for bandwidth bound workloads, but won't do anything for latency sensitive ones. A stacked L3 cache or the L4 cache introduced for some Haswell SKUs doesn't have that drawback. It's equally useful for both types of workloads, but has the tradeoff of lower capacity when compared to HBM.

 

[Artas1984]

The Core i7 5775C should have had 95 W TDP and 4.0 GHz base clock... You could play StarCraft 2 on it's Iris Pro iVGA on 720p resolution though...

 

[Wirko]

HBM will be useful for bandwidth bound workloads, but won't do anything for latency sensitive ones. A stacked L3 cache or the L4 cache introduced for some Haswell SKUs doesn't have that drawback. It's equally useful for both types of workloads, but has the tradeoff of lower capacity when compared to HBM.

Intel's Crystal Well L4 cache does have the same drawback, its latency doesn't come close to static RAM:

 

[Macro Device]

should have had 95 W TDP and 4.0 GHz base clock...

What for? People aiming for ultimate gaming performance would end up buying a Z mobo and overclocking every piece of silicon out this poor CPU anyway. Others don't care, they paid for other features.

 

[R-T-B]

Devil NUC

Can't help but lol at that name...

 

[Mussels]

Now (now?) Intel has Sapphire Rapids with HBM, and that HBM can be one of three things: extension to RAM, the only RAM in the system, or cache.
That's probably intended for customers who order processors literally by the metric ton, so they won't have a retail price tag.

As AnotherReader said, HBM is high bandwidth but has latency problems.
Combining this L4 cache in between is exactly what they could be doing.

Intel bet a lot on optane and it flopped, it's why i think they'll do what they can to leverage existing technologies from their past if possible.

 

[AnotherReader]

Intel's Crystal Well L4 cache does have the same drawback, its latency doesn't come close to static RAM:

That's true, but it is much better than HBM or just about any kind of DRAM sold as standalone packages. Most of the latency is due to the off-chip connection and the large size of the array and some is due to the DRAM. Keep in mind that DRAM caches can be very fast too if they are on-chip.

Addendum: for large memories, wire delay matters more than the cell delay. This is why L3 caches are slower than L2 despite using SRAM.

​

Mem Hierarchy	IBM POWER8	Intel Broadwell Xeon E5-2640v4 DDR4-2133	Intel Broadwell Xeon E5-2699v4 DDR4-2400
L1 Cache (cycles)	3	4	4
L2 Cache (cycles)	13	12-15	12-15
L3 Cache 4-8 MB(cycles)	27-28 (8 ns)	49-50	50
16 MB (ns)	55 ns	26 ns	21 ns
32-64 MB (ns)	55-57 ns	75-92 ns	80-96 ns
Memory 96-128 MB (ns)	67-74 ns	90-91 ns	96 ns
Memory 384-512 MB (ns)	89-91 ns	91-93 ns	95 ns

Table from Anandtech's Power 8 review

Latency of MCDRAM compared to DDR4 (about 10% higher)

 

[Artas1984]

What for? People aiming for ultimate gaming performance would end up buying a Z mobo and overclocking every piece of silicon out this poor CPU anyway. Others don't care, they paid for other features.

What for? So it would not look weak vs. i7 4790K and i7 6700K. And that is exactly what i did - used i7 5775C on Z97 system and overclocked it to 4.2 GHz, but wished so much more! The fact that most people would still overclock i7 5775C makes my argument for a higher TDP valid, as the majority of folks used it for gaming, and the minority used it for their low tier mini workstation builds with no dedicated GPU.

 

[Macro Device]

The fact that most people would still overclock

Source? Back in the day it was VERY unlikely to hear about BW from anyone who's not a complete nerd and 2015 gamers were too obsessed with GTX 980 Ti for 5775C to be meaning something. Not to mention how little performance gains were from that L4 cache in then-modern games.

The fact your personal CPU was able to run at 4.2 GHz means nothing in global. New arch binning is not like "well let's push it to a million gigahertz and sell it that way."

 

[Mussels]

Source? Back in the day it was VERY unlikely to hear about BW from anyone who's not a complete nerd and 2015 gamers were too obsessed with GTX 980 Ti for 5775C to be meaning something. Not to mention how little performance gains were from that L4 cache in then-modern games.

The fact your personal CPU was able to run at 4.2 GHz means nothing in global. New arch binning is not like "well let's push it to a million gigahertz and sell it that way."

Overclocking is *still* a rare and niche thing, the mining boom brought it to public awareness but the common conception is still that 'it makes your PC unstable and kills your hardware'

 

[rockit00]

I bumped into one of my old hardware suppliers today. They sell OEM intel stuff and have brand new tray i7 5775C CPU's for a reasonable price. They also have a lot of boxed intel vintage CPU's and motherboards. I once owned an i5 5675C and used it to test my Z97 and H87 rigs for compatability. It was expensive and I didn't overclock or tinker too much with it. If any of you want I can send a link to the supplier.

 

[LabRat 891]

I bumped into one of my old hardware suppliers today. They sell OEM intel stuff and have brand new tray i7 5775C CPU's for a reasonable price. They also have a lot of boxed intel vintage CPU's and motherboards. I once owned an i5 5675C and used it to test my Z97 and H87 rigs for compatability. It was expensive and I didn't overclock or tinker too much with it. If any of you want I can send a link to the supplier.

I do want, but
I have neither the discretionary funds nor the time to collect more stuff; I already told myself that I'm sticking to AMD, ATI, Cyrix, and VIA for my 'collecting' anyway...

So yeah, I'd love a link!

(At the least, I can oogle some)

 

[Fouquin]

I bumped into one of my old hardware suppliers today. They sell OEM intel stuff and have brand new tray i7 5775C CPU's for a reasonable price. They also have a lot of boxed intel vintage CPU's and motherboards. I once owned an i5 5675C and used it to test my Z97 and H87 rigs for compatability. It was expensive and I didn't overclock or tinker too much with it. If any of you want I can send a link to the supplier.

Hmmm that sounds interesting. Do share.

Cyrix, and VIA

And all that blends in between. I will say that collecting VIA stuff post-Centaur closure has been much more fun since we have all the strange unreleased hardware on the market. Though as expected it's starting to dry up.

 

[LabRat 891]

And all that blends in between. I will say that collecting VIA stuff post-Centaur closure has been much more fun since we have all the strange unreleased hardware on the market. Though as expected it's starting to dry up.

I almost bought some "IBM" and "National Semiconductor" 'cyrix' CPUs a few months back. Sadly, I have 0 supporting hardware for it (other than some PC100 and PC133 SDRAM).

While I might eventually reach back to the DOS/WinX.X era of hardware my personal 'enthusiast experience' started thereabouts the Pentium III era. (Which, for that era, I have a 1ghz C7 embedded ITX board, and a menagerie of AMD Socket A kit.)

I can accept (though, with a pang) the fact I'll probably never have many of those early x86 CPUs; most of them get sold for gold scrap

 

[AusWolf]

I bumped into one of my old hardware suppliers today. They sell OEM intel stuff and have brand new tray i7 5775C CPU's for a reasonable price. They also have a lot of boxed intel vintage CPU's and motherboards. I once owned an i5 5675C and used it to test my Z97 and H87 rigs for compatability. It was expensive and I didn't overclock or tinker too much with it. If any of you want I can send a link to the supplier.

I'm interested too. I have way more "collectibles" than I need or should have, but such a rarity is welcome, if the price is right.