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DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

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Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#71

Post by ksec »

The unanswered question is, will it be cheaper?

Price / GB of DRAM hasn't actually fallen much in the 10 years of progression.[1] LPDDR is still over $3/GB. UDIMM is still ~$3 /GB, which is about the same in 2010 / 2011. i.e Despite what you may heard about DRAM price collapse in 2019, the price floor of DRAM has been pretty much the same over the past 10 years.

Every other silicon has gotten cheaper, NAND, ICs, just not DRAM. And yet our need for DRAM is forever increasing. From In-Memory Datastore on Servers to Mobile Phones with Camera shooting rapid 4K images.

Compared to NAND, or Foundry like TSMC, there are clear roadmaps where cost is heading, and what cost reduction we could expect in the next 5 years, along with other outlook. There is nothing of sort in DRAM. At least I dont see anything to suggest we could see $2/GB DRAM, if not even lower. I dont see how EUV is going help either, there won't even be enough EUV TwinScan machines going around for Foundries in the next 3 years, let alone NAND and DRAM.

The only good news is the low / normal capacity ECC DRAM has finally fallen to ~$5/GB. ( They used to be $10-20/ GB ).

[1] https://secureservercdn.net/166.62.107.55/ff6.d53.myftpuploa...

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#72

Post by wegs »

zionic wrote: post #52
orliesaurus wrote: post #6

Yeah, but to the casual user like me, that's going to help with load times... go from 2 seconds to 1 second.

Be more excited that ECC is now part of the standard, and without a speed compromise.

Does this mean it will work on any motherboard?

On the whole, I find these 20% performance memory upgrade (leading to a fraction of that in real-world performance) more obnoxious than anything, but I'd love ECC!

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#73

Post by formerly_proven »

gameswithgo wrote: post #36
Macha wrote: post #15

Earlier quoted context omitted.

Depends a lot on your CPU's architecture as well as workloads, how far ahead it prefetches vs how often it's stalled on large memory reads. So it's hard to know. e.g. Zen+ (Ryzen 2000) was seeing 10% in some gaming workloads going from DDR4-2400 to DDR4-3600, but it's much less drastic on Intel CPUs or even Zen 2 (Ryzen 3000) because the memory controller is smarter so the slower RAM is less of a detriment. And then…

The reason Zen1 (and 2) speed up a lot from ram speed increases is because the memory controller speed is tied to ram speed. So when you bump up the ram speed you also bump the memory controller speed, which reduces ram latency and inter-cpu communication latency. There is no telling what the memory controller -> ram ratio will be with ddr5, the memory controller has speed limits, so you aren't going to get free spee…

Zen 2 IMC can do DDR4-5000, but it's rather pointless, because it requires un-coupled mode with IFCLK != UCLK (since IFCLK cannot be pushed to more than ~1.9 GHz, and even that is not stable on many CPUs), which adds so much latency that you _need_ DDR4-5000+ to approach the performance of DDR4-3800 with IFCLK = UCLK.

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#74

Post by [deleted] »

gnarbarian wrote: post #68
morceauxdebois wrote: post #2

I'm happy that I put off upgrading my pc long enough to skip a RAM generation.

I try to refresh when a new ram gen launches with a new socket. That gives me a good shot at long term upgradability. Waiting on zen 4 now for my next complete build.

[deleted]

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#75

Post by CyberDildonics »

zdw wrote: post #38
Zenst wrote: post #35

I like what IBM has done with their latest power chip - effectually made the whole memory interface upgradable. https://www.nextplatform.com/2020/09/03/the-memory-area-netw... "the shift from dedicated DDR4 memory controllers to Serdes-based, high speed differential signaling mixed with buffer chips on memory modules that can be taught to speak DDR4, DDR5, GDDR6, 3D XPoint, or whatever, is an important shift in syste…

Adds a latency hop, which generally can be dealt with by prefetching and larger caches on the CPU side. There's speculation that AMD is going to do the same - in Zen 2 and later designs the CPU chiplets are coupled with different IO dies depending on the design (Ryzen, Threadripper, Epyc), and swapping out the IO die for one that has support for new/different memory types would less work than taping out a whole new m…

Why does it add a latency hop?

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#76

Post by DCKing »

One thing I'd like to understand better about DDR5 is how well the built-in ECC is going to work to improve reliability. DDR5 comes with "chip level ECC" [1] of which the main purpose is to be able to better sell highly complicated memory chips with minor defects.

But as a consequence as I understand, it will allow for the correction of single bit memory flips. With regular DDR4 or previous generations, you don't get any error correction. Any bit error in your DDR4 modules has the potential to corrupt data. If you want to be protected from that, you will need to get ECC memory.

Unfortunately, anything with "ECC" in hardware for unfortunate reasons gets labeled with an "enterprise" sticker. And that means a certain price level, and a certain power consumption. (Yes I know you can get Ryzen boxes that work with ECC, but that's still PC sized hardware for hundreds of dollars).

If DDR5 can bring error correction to the masses - like in single board computers, 10W NAS boxes, smartphones - that would be pretty cool. But I'm not sure whether my reading of that is correct.

[1]: https://www.anandtech.com/comments/15912/ddr5-specification-...

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#77

Post by monocasa »

dragontamer wrote: post #48
NikolaeVarius wrote: post #42

Earlier quoted context omitted.

Not really. They plan to try to make "as many PS4 games BC as possible" which means they are actively porting games they deem worth porting, versus it being natively supported

PS5 is an x86 CPU + AMD RDNA GPU. PS4 was an x86 CPU + AMD GCN GPU. A huge amount of games will be portable from the get-go. GCN and RDNA have extremely similar assembly languages. The only major assembly language change from GCN -> RDNA is DPP / cross-lane operations (kinda like pshufb from x86). But I'm not even sure if the PS4 had those instructions.

It's deeper than that, the shaders are _binary_ compatible.

> The only major assembly language change from GCN -> RDNA is DPP / cross-lane operations (kinda like pshufb from x86). But I'm not even sure if the PS4 had those instructions.

Yeah, it didn't. AFAIK, they were added in GCN 3, while the PS4 is GCN 1.1.

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#78

Post by tw04 »

ksec wrote: post #71

The unanswered question is, will it be cheaper? Price / GB of DRAM hasn't actually fallen much in the 10 years of progression.[1] LPDDR is still over $3/GB. UDIMM is still ~$3 /GB, which is about the same in 2010 / 2011. i.e Despite what you may heard about DRAM price collapse in 2019, the price floor of DRAM has been pretty much the same over the past 10 years. Every other silicon has gotten cheaper, NAND, ICs, just…

It seems nearly impossible that they aren't back to price fixing.

https://en.wikipedia.org/wiki/DRAM_price_fixing

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#79

Post by monocasa »

NikolaeVarius wrote: post #53
dragontamer wrote: post #48

Earlier quoted context omitted.

PS5 is an x86 CPU + AMD RDNA GPU. PS4 was an x86 CPU + AMD GCN GPU. A huge amount of games will be portable from the get-go. GCN and RDNA have extremely similar assembly languages. The only major assembly language change from GCN -> RDNA is DPP / cross-lane operations (kinda like pshufb from x86). But I'm not even sure if the PS4 had those instructions.

That isn't the original point. The PS4 is not natively backward compatible, the base game needs to be ported. Native BC would be 1. It runs native hardware (PS2 EE on Early PS3) 2. It runs without updates required (PS2 running inside emulator on later PS3) This requires actual updates by the dev for individual games to work

Or it's _really_ close, but the systems are complex enough that they feel they need to QA/cert the games again even if the vast majority of games require no changes.

Re: DDR5 Is Coming: First 64GB DDR5-4800 Modules from SK Hynix

#80

Post by Sebb767 »

brixon wrote: post #11
nullifidian wrote: post #3

Will we get performance increases, and how big will they be in the average case, not for some specific codes with low cache hit ratio on large datasets, and attributed solely to bandwidth increases and not architecture IPC improvements?

"For bandwidth, other memory manufacturers have quoted that for the theoretical 38.4 GB/s that each module of DDR5-4800 can bring, they are already seeing effective numbers in the 32 GB/s range. This is above the effective 20-25 GB/s per channel that we are seeing on DDR4-3200 today." That looks like a 20%+ improvement IF you are bottle-necking on DDR4.

So, it's worth upgrading if you're running Redis or Dwarf Fortress :)
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