Specifications: DDR2 Memory

Considering the delays and false starts with DDR2, we were surprised to receive DDR2 modules from 8 different manufacturers for our first DDR2 roundup. The DDR2 from Corsair was even rated at DDR2 667, which caused us to believe that the Corsair would stand head and shoulders above the crowd. We also know of other DDR2 667 samples that are on the way from OCZ and others that will soon be announced. For memory that was barely working a couple of months ago, it certainly appears that DDR2 is maturing much faster than anyone expected.

The 8 DDR2 memories that we received were all rated at or near the Jedec standard for PC2-4300 of 4-4-4-12 timings. Jedec standards for PC2-5300 (DDR2 667) call for 5-5-5 timings, but our Corsair DDR2 667 was rated at the faster 4-4-4, at 667, which already shows improving timings for DDR2.

 Memory  Number of DIMMs & Banks  DIMM Size
Total Memory
 Rated Speed
SPD Timings
 Rated Voltage
Corsair XMS2
5300 PRO
2 DS 512MB
1GB
DDR2-667
4-4-4-12
1.8V
Crucial
PC2-4300U
2 DS 512MB
1GB
DDR2-533
4-4-4-12
1.8V
Geil
PC2-4300
2 SS 512MB
1GB
DDR2-533
4-4-4-11
1.8V
Kingmax
DDR2-533
2 SS 256MB
512MB
DDR2-533
4-4-4-12
1.8V
Kingston
PC2-4300
Value RAM
2 SS 512MB
1GB
DDR2-533
4-4-4-12
1.8V
Micron
PC2-4300U
2 DS 512MB
1GB
DDR2-533
4-4-4-12
1.8V
Mushkin
DDR2 533
2 SS 512MB
1GB
DDR2-533
4-4-4-12
1.8V
OCZ Premier
PC2 4300
2 SS 512MB
1GB
DDR2-533
4-4-4-11
1.8V

The SPD timings were closely bunched around the 4-4-4 Jedec standard, and all the tested memory was rated at the standard DDR2 voltage of 1.8V. Unlike the standardized DDR memory, we received a mixed bag of single- and double-sided memory, even in the same memory capacity. Memory based on Micron chips, like the Micron, Crucial, and Kingmax, were rated 256MB single-sided and 512MB double-sided. Those based on Samsung, like the OCZ Premier, or Elpida, like the Kingston Value RAM, were 512MB single-sided. Double-sided 1GB modules based on these memory chips are therefore likely to appear in the very near future.

We also received 1GB DDR2 memory modules from OCZ, but these early samples were based on Samsung chips. OCZ has decided recently that Elpida chips will be used for their 1GB DDR2 modules, so we eliminated the 1GB DIMMs from our roundup, since they are not representative of production DDR2. While 1GB modules have remained rare and expensive in DDR memory, you will likely find 1GB memory widely available from many DDR2 manufacturers in the very near future. Several manufacturers also plan to introduce 2GB DIMMs in DDR2.

Another difference in DDR2 compared to DDR is the last memory timing number, or tRAS. As we have demonstrated in our DDR reviews, Intel 875/865 chipsets have performed best at the fastest tRAS settings that could be used on the motherboards. This was normally a tRAS value of 5 or 6. DDR2, on the other hand, has a specified tRAS of 11 or 12 in most cases. Does tRAS matter on DDR2 or have the performance rules changed with DDR2 memory timings?

Index tRAS and DDR2
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  • betatest3 - Wednesday, August 18, 2004 - link

    The DDR2 667 memory is allready available and price is around $245 to $270 for 512mb .The only memory I found was made by Crucial and some Generic by doing a search on pricewatch.com site The $245 memory can be seen here -->
    http://www.newegg.com/app/viewproductdesc.asp?DEPA...

    Hmm.. this DDR2 memory was just made for Intel ??? or maybe in newer motherboards can be used with AMD also ? I would not think a newer memory made by many company's would just be designed for intel especially when alot of manufacturers are jumping over to AMD or can AMD use this 667 memory ?
    Reply
  • jiulemoigt - Monday, July 12, 2004 - link

    A very funny thought aquired to me after reading the older article on AMD's DDR2 stance. If their waiting for DDR2 667 and the memory is ready but quitly being called 533 does that mean AMD may actully be ready to pull a fast on Intel? Considering the way the chip is designed could the memory controller be flashed to update to the memory controller the same way the other frequencies are set? Oh and I would not buy a LGA socket the pin's being spring loaded just looks to be trouble :o cool article Reply
  • Wesley Fink - Friday, July 09, 2004 - link

    FlameDeer -

    Good catch. P. 6 is corrected to 1032FSB.
    Reply
  • FlameDeer - Friday, July 09, 2004 - link

    Thanks for quick respond at #10, Wesley! :)

    Really appreciate your hours and hours of hard work to publish this very first hand thorough DDR2 roundup! :)

    A quick look again of this good article, I noticed something need to ask. In page 7 till page 14, is that "258FSB" of 686DDR in every table mean 4 x 258 = "1032FSB"? And is this FSB related to page 6 settings no.3 of "1016FSB/DDR2-686"? Just curious, thank you! :)
    Reply
  • pookie69 - Friday, July 09, 2004 - link

    Cool - i think i understand that now.

    Thanks for replying and explaining. Appreciated :)
    Reply
  • Wesley Fink - Friday, July 09, 2004 - link

    The ratio is 3:4 looking at base clocks (200 to 266). The bus is then quad-pumped to 800 and memory is DOUBLE Data Rate or 533. I do agree it is a bit confusing since the final 800 ratio is 3:2 of the final DDR2 ratio (533).

    The 975/865 standard was 1:1 since the base clocks are 200, even though the final speeds were 800FSB (quad) and 400 DDR. It was never called 2:1.

    Reply
  • pookie69 - Friday, July 09, 2004 - link

    Nice article - good job :)

    Only one point; where it reads;

    "This is currently slightly below the memory timing of 250 required to run memory at DDR2 667, at the standard 3:4 Intel memory ratio for DDR2."

    >>> shouldn't that be a 3:2 ratio?

    Or am i confused :S

    Nice article again - keep up the good work Mr. Fink ;)
    Reply
  • TrogdorJW - Friday, July 09, 2004 - link

    I think a better conclusion might have been: And the winner is... NO ONE! (Or everyone, depending on whether you see the glass as half full or half empty.) While there are definitely measurable differences in performance between the various memories, reality is that only Quake 3 and Enemy Territory are meaningful benchmarks. Seeing that Quake 3 is one of the most bandwidth hungy games of all time, it's rather telling that a 15.4% advantage in Sandra only equates to a 2.7% performance difference in Quake 3 (and even less in W:ET). I'm not criticizing your work, mind you - just pointing out that the best case scenario of Sandra Unbuffered RAM tests are not the way we actually use our systems.

    At some point, it would be nice to see a memory roundup that included all the benchmarks that are used in CPU and graphics comparisons. Obviously, that wouldn't be a prudent use of your time when we're still being limited by the motherboard. However, in another six months, I would like to see a memory comparison put together that broadened the field of view in regards to benchmarks.

    Great article, though. It will certainly be interesting to see how far each memory type can actually overclock when the motherboard is no longer the limiting factor. For the present, though, it looks like we might as well just save our pennies and buy cheaper DDR2 modules. (Not that any of them are actually "cheap"....)
    Reply
  • Pumpkinierre - Thursday, July 08, 2004 - link

    I suppose with all these new goodies, Wesley, you are going to give up on the excellent straight DDR articles you used to do.

    For the tRAS, the usual formula for DDR is: tRCD+CAS latency + 2 cycles, see:
    http://www.mushkin.com/mushkin/pop-up/latencies.ht...
    So that seems to work for DDR2 at tRAS >10. I dont know why DDR2 still works at tRAS of 4 though. I also dont know why nForce chipsets have their tRAS so high (10-12) on ordinary DDR.

    You've got an engineering sample (multiplier unlocked) Prescott that o'clocks well. So you ought to do some tests at same CPU speed but different FSBs like you have done on the a64s. I know you might think it is stupid given that retail cpus are multiplier locked but some of us want to see whether it is better to put more money in a higher grade cpu or get a cheaper one and o'clock it high using more expensive high speed low latency memory. You had'nt done this with the N'wood/i875 memory tests either, but I cant remember whether you've got a good N'wood engineering sample lying around. Anyway just a suggestion.
    Reply
  • ariafrost - Thursday, July 08, 2004 - link

    Now if only DDR2 latencies were lower and the pricetag was less than DDR1 :) Reply

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