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Discussion: Nehalem memory details

Discussion: Nehalem memory details

Medicore clock speeds and high CAS, but still with plenty of bandwidth to spare, it seems...

Instead of just a quick news piece this has turned into a bit more of an in depth discussion about what we expect to happen with Nehalem/Bloomfield and the memory market when it arrives very soon. We've known for a little while that Nehalem's memory will only run at 800MHz or 1,066MHz opposed to the usual 1,600MHz+ that we have now, but the usual motherboard manufacturers are working on a "1,333MHz OC" option which most of them already have running fine (so we hear).

The problem is people might perceive this as slow and it will cause a bit of a pickle for memory vendors who rely on performance margins for marketing material.

DDR3 memory today will easily work at 1,333MHz speeds, but the news through the grapevine is that Intel is going for a low power emphasis so overclocking the memory will be harder. In fact, from quite a few sources in Taiwan, we've heard that Intel is more than happy with CAS-9 at 1,066MHz which is slow.

It's been strongly suggested by others that Nehalem's memory voltage will be directly linked and possibly the same as the CPU voltage - limiting the amount of beans you can force through your memory, however we're almost certain this is not the case. You'll be limited by how much memory controller (aka northbridge) voltage you can use and this will be tied to the CPU voltage at a particular ratio as the memory controller and CPU voltage planes are different. This is evident by Intel's admission already. If the P45 northbridge is anything to go by, you don't need that much extra voltage anyway so the vast majority of us will be OK, however the most extreme overclockers might cry foul.

Like we've already shown in our early looks, the actual memory voltage on X58 boards is controlled by two or three phases on the motherboard - so actual DDR3 voltage will be independent. You'll be limited by what memory multipliers you can run, but that's not different than what's currently available on Intel platforms and keeping everything tied into a small number of variations means the internal latency is minimised.

So while we'll be not hitting super high memory frequencies, we should be able to hit low CAS numbers from performance memory instead - CAS-5 at 1,333MHz will do nicely, thanks. It'll be back to the days of DDR where there was not much overhead left and memory was sold on its low CAS as much as its capability to do super high clocks. This is on the proviso that Intel's integrated northbridge mimics the way P45/X48 can easily achieve low latency numbers, whereas in contrast Nvidia' nForce 790i Ultra SLI prefers a high clock and high latency design. We've already found DDR3 at 1,600MHz and CAS-6 gives almost the same memory efficiency as 2000MHz at CAS-9.

Also, since Nehalem has cut out the archaic, latency heavy front side bus for a direct connect approach like AMD, we've heard from industry insiders that triple channel DDR3 will hit "14,000MB/s easily in Everest" (which is typically single core loading software). Intel also showed off Nehalem setups executing 22GB/s of bandwidth at IDF for "STREAM triad multi-threaded" tests, which is basically a more "real world" approach that factors in read, write and modify data to memory. We've no idea of what latencies and speeds the memory was running, however since 1,333MHz OC has only been QA'd recently in Taiwan, we'd hazard a guess these numbers represent the standard 1,066MHz variety.

Our guess is to look out for memory vendors advertising 3GB and 6GB triple-channel kits in the next month or so sporting ever lower CAS numbers rather than high clocks. This is how we expect them to try and make their margins for premium kits. It will be interesting to see how extreme cooling the CPU can affect the memory controller ability too, or if the complex eight layer PCB and triple channel DDR3 is the limiting factor - motherboard design might play a key factor as much as BIOS development in the forthcoming months.

The memory controller is unlikely to change between Bloomfield and Lynnefield/Havendale and with Lynnefield and Havendale, we're not going to have triple channel memory to make up the numbers - dual channel DDR3-1066 sounds slow but Intel are not going to let its mainstream CPUs out perform its Bloomfields that will charge the margin for "enthusiasts" - will it just have one channel disabled? Can you turn it on in future CPUs? The memory controller may not even change with future core revisions of Bloomfield, unless there are so many cries from hardcore overclockers and performance enthusiasts, but we expect controller changes allowing faster memory will require new board qualifications and PCB testing - Intel likes to make sure everything works solidly first and foremost.

Considering how intimately the power regulation features are tied to all components of a new CPU, we can't see this as a viable task either. Couple into the fact that the performance sector is tiny, it's unlikely that the cost and time: marketing benefit and revenue ratio will be in our favour. If AMD had something to challenge the performance crown there would be far more of an incentive, however we can't see that happening even with Shanghai. So this looks like the status quo for a while yet, so once new memory kit prices level out expect it to be an investment that should last a while.

Are you waiting for triple-channel kits of DDR3 specially designed for Nehalem? Let us know in the forums.

20 Comments

Discuss in the forums Reply
biebiep 4th September 2008, 18:18 Quote
I'll skip this one and wait for 32nm nehalem :)
I've always preferred 'Tocks' over 'Ticks' as Intel likes to call them... And i'm not too confident about first-gen mobo's getting the most out of this one ;)

But seriously... 14K mb/s for the budget version... The basic-budget version of thet next generation has more than the mainstream version of this generation xD. That's how we like to see it! Gratz to Intel! (omy, did that just sound fanboyish?)
naokaji 4th September 2008, 18:46 Quote
is the 1066 the actual max speed supported though or is it just intel being scared of going above jedec specs? I was planning to get another 2GB Cellshock 1866 to have 6GB with nehalem, I sure hope 1066 wont be some kind of hard limit.
Tim S 4th September 2008, 18:51 Quote
1,066 is the maximum memory clock for a stock Bloomfield, that's for sure.
bowman 4th September 2008, 19:06 Quote
biebiep, tock is Nehalem, tick is Westmere. :)

Oh well, I'll wait and see. Either Nehalem will be worth the money, or I'll just go for subsequent downpriced Penryn quads.
biebiep 4th September 2008, 19:13 Quote
Quote:
Originally Posted by bowman
biebiep, tock is Nehalem, tick is Westmere. :)

Oh well, I'll wait and see. Either Nehalem will be worth the money, or I'll just go for subsequent downpriced Penryn quads.

Woops my mistake.

But yeah, Nehalem's first punches are going to have to be very hard ones. Since a Q9650(heck, even a good ol' OC'ed Q6600)+P45 board is a hard-to-beat combo when priced down to make room for Nehalem :p
oasked 4th September 2008, 20:43 Quote
Quote:
Originally Posted by biebiep
But yeah, Nehalem's first punches are going to have to be very hard ones.

From all accounts, I think they will be very hard punches. The trouble is, like most prize fighters, you won't be able to afford to hire one.
(AFAIK The first Nehalem's will be the "Extreme Edition" parts Q4 2008, then the mainstream will come Q1 and Q2 2009).
Faulk_Wulf 4th September 2008, 22:35 Quote
Okay maybe I am retarded, but I thought that only 64-bit Vista could use the max 4GB of memory we have available now. So what's the point of 6GB of memory if nothing can be accelerated by it? Wouldn't 6GB in 64-Bit be as redundant as 4GB in 32-Bit? Or am I missing something obvious here?
The Jambo 5th September 2008, 00:07 Quote
Vista 64-bit can handle up to 128 GB of Memory, hence the much needed switchover to x64.

Join the x64!
seanap 5th September 2008, 00:09 Quote
The jambo beat me to it!
seanap 5th September 2008, 00:09 Quote
The jambo beat me to it!
Sublym3 5th September 2008, 02:49 Quote
Other websites reported that Intel is just sticking to Jedec standards, so there is no 'offical' support for faster memory.
p3ri0d 5th September 2008, 03:33 Quote
Actually with 64bit os's the memory limit depends on the rest of the hardware (Motherboard, processor, etc.) but theorically it can support 16 exabyte of ram :D

(16 exabyte = 16.8 million terabyte)

http://en.wikipedia.org/wiki/64-bit#Memory_limitations
woodshop 5th September 2008, 03:37 Quote
i'm still waiting for the return of the 1:1 cpu memory relationship..
biebiep 5th September 2008, 08:24 Quote
Quote:
Originally Posted by oasked
Quote:
Originally Posted by biebiep
But yeah, Nehalem's first punches are going to have to be very hard ones.

From all accounts, I think they will be very hard punches. The trouble is, like most prize fighters, you won't be able to afford to hire one.
(AFAIK The first Nehalem's will be the "Extreme Edition" parts Q4 2008, then the mainstream will come Q1 and Q2 2009).
Mostly in optimized multi-threaded apps, so that means games are less likely to improve...
Also, the lower L2 cache on nehalem makes it a less optimal for gaming(comparing to Core's massive L2's), so i'm still not convinced that Nehalem will WTFBBQPWN the Penryns in gaming :p
Kúsař 5th September 2008, 09:36 Quote
Athlons are using 800MHz DDR2 and they have pretty high mem bandwidth. Now that intel has integrated mem controller into CPU, it shouldn't be surprising :)
yakyb 5th September 2008, 11:04 Quote
i wouldnt' be suprised if the uptake on nehalem is pretty slow tbh i would much rather buy a q6600 and some cheap 4GB kit of ddr2

when nehalem is shrunk and ddr3 is cheaper then i might re-appraise
mclean007 5th September 2008, 11:33 Quote
Quote:
Originally Posted by woodshop
i'm still waiting for the return of the 1:1 cpu memory relationship..
Easy - underclock your CPU to 1,333 MHz and see how fast it goes.
naokaji 5th September 2008, 12:47 Quote
Quote:
Originally Posted by Faulk_Wulf
Okay maybe I am retarded, but I thought that only 64-bit Vista could use the max 4GB of memory we have available now. So what's the point of 6GB of memory if nothing can be accelerated by it? Wouldn't 6GB in 64-Bit be as redundant as 4GB in 32-Bit? Or am I missing something obvious here?

64 bit vista (like all other 64bit os's) supports way more than 4 GB, only a 32 bit os will pose a limit.
there is also the physical limitation of todays mainboards, you have 4 slots on the s775 boards, with 2 GB modules being the biggest ones avalaible (there are bigger ones, but they are a) insane expensive and b) slow).
Current intel chipsets have a dual channel controller, so its either 2 or 4 modules.
I went with 4 1GB modules because they oc better than 2 2GB modules.
Nehalem will have a triple channel meory controller, so its a) downgrade to 3GB or b) upgrade to either 6 or 12.
SuperNova 6th September 2008, 15:45 Quote
The price could play a big role in this too. 3GB isn't enough for this CPU, so 6GB will be the spot to aim for (bloomfield is an enthusiast CPU after all). The tripplechannel will deliver enough bandwidth for a while, even at 1066MHz so i can understand why they settle for 1066MHz especially when you consider the price on lets say 1600 or higher specced DDR3 modules. 3x2GB @ 1600MHz++ is expensive, you will basically put more money into the memory than you will for the 2.66GHz CPU (with todays memory prices).

Then you have the problem with many modules at high speeds. 4x2GB DDR2 @ lets say PC8500 isn't exactly stable on the majority of the boards. NO manufacture (from what i have seen) have added this config in their "support-lists". Since you have three channels you have to have in mind that some people will put 6 modules on the board. 6 modules @ 1600+ speeds would probably create some stability issues.

So the bottom line is that you market the cpu with 1066MHz support which is "safe" at the same time people will lock for 1066MHz memorys which is far cheaper than the once with higher clocks like 1600Mhz. The 1333Mhz seems to be a mystery though since the price difference isn't that big between them. 1333Mhz seems to the a spot where you could get it to work, but i bet intel goes for the "better safe then sorry" approach on a new architecture.
wuyanxu 7th September 2008, 09:46 Quote
the memory speed isn't really as important as how much there is.

8GB at 800Mhz will win 4GB at 1066Mhz most of the time in real world performance. so 6GB at 800Mhz should be the minimal. and if they offer 12GB tri-channel kit, i'll probably be the first one to buy those, even if it's "only" 800Mhz.

with 3 levels of caches, memory speed isn't as important as before, so why so bothered about the benchmarking bandwidth?
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