1GB DDR DIMMs began appearing in the market over a year ago. Since that time, one of the most - asked questions from our readers is whether they should buy 512MB or 1GB DIMMs.

The answer to that question has not been easy up to now. On the one hand, two 1GB DIMMs on the AMD Athlon 64 could still run at 1T Command rate, instead of the 2T required by the 4x512MB DIMMs needed for 2GB with 512MB DIMMs - a definite advantage for the 1GB DIMMs. On the other hand, the available 1GB DIMMs were generally much slower than the fast 2-2-2 DIMMs that were commonly available in 512MB DIMMs. We normally saw 3-3-3 or 3-4-4 or slower timings for 1GB DIMMs. These poorer timings for 1GB DIMMs took away most of the advantage for the 1GB 1T Command Rate.

There was an additional "gotcha" with the 1GB DIMMs that many enthusiasts quickly discovered. With a starting point of 3-3-3 or 3-4-4, the 1GB parts did not overclock nearly as far as the 512MB parts. For all of these reasons, we had generally recommended that most users were better off with 512MB DIMMs - at least until memory timings improved on the 1GB DIMMs.

The time for faster 1GB DIMMs has finally come, and they are starting to appear from many recognized and a few new manufacturers. Since there were so many questions about whether the 1GB DIMMs were a wise choice for Athlon 64 buyers, we looked at three very different 1GB parts supplied as a 2GB kit - or 2 1GB DIMMs. These are the Corsair CMX1024-3500LL PRO (DDR433), Gigaram 2GB Dual Channel PC-4200 (DDR533), and OCZ PC4000 1024MB EB Platinum (DDR500).

 Manufacturer  Description
(Memory Chips)
 Memory Speed  Rated Timings  Voltage
Corsair CMX1024-3500LL PRO
433DDR 2-3-2-8 2.6V
Gigaram 2GB Dual Channel PC-4200
533DDR 3-4-3-8 2.9-3.0V
OCZ PC4000 1024MB EB Platinum
(Probably Infineon)
500DDR 3-3-2-8 2.6V

Our memory tests differentiate memory in two ways. First, AnandTech has always been an advocate of real world performance measurements, and we've shunned using just synthetic benchmarks in our testing of every type of component, including memory. This is not because synthetic benchmarks are not useful - they are often very revealing of component differences. It is because running just synthetic benchmarks can severely distort the picture of performance with real applications and real games. That is why we always use games and the pure number-crunching Super Pi in our memory tests. It is also the reason why we test using both Buffered (Standard) and Unbuffered synthetic benchmarks. We have found in much of our testing that the less commonly used Unbuffered benchmarks more closely mirror how games really respond to memory differences.

Second, we moved to testing different memory speeds at the same CPU clock speed in our Athlon 64 memory tests. The AMD CPU, with unlocked multipliers, allowed us to finally remove the CPU speed differences from our memory tests. This allows you to see the true impact of memory speed increases and memory timings on performance. As you have seen in past reviews, those performance differences are very real, although they are much smaller than many memory manufacturers might want you to believe. On the other hand, faster memory speeds and faster memory timings do improve performance, no matter what some nay-sayers are determined to prove.

Using these tests, we expected that the wide range of specifications for these 1GB DIMMs would allow us to differentiate which type of specification would best fit certain end users' needs, and easily pick a winner. Along the way, however, we found that things are not always as they appear, and this is particularly true in the high-end memory market.

Why 1GB DIMMs?
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  • Slaimus - Tuesday, October 11, 2005 - link

    Does 4 single sided 512MB sticks behave the same as 2 double sided 1GB sticks?
  • eastvillager - Tuesday, October 11, 2005 - link

    Why would you buy these when the 2-3-2-5 sticks are readily available?
  • Wesley Fink - Tuesday, October 11, 2005 - link

    If you read the review you will see that ALL THREE of the 1GB dimms ran at 2-3-2 at DDR400 to DDR440 or so. They will all run 2-3-2-5, but we have shown in previous tests the the nForce 4 is fastest running a tRAS of 6 or 7. We ran 2-3-2-7 because it is faster than 2-3-2-5 on the nForce4. Try it for yourslef with memtest86 and differnet tRAS.
  • Sunrise089 - Tuesday, October 11, 2005 - link

    Possible minor typos aside, this article is a great change of pace from some of the recent technical write-ups here on Anandtech(cough:R520:cough). The quality of writing as well as the attempt to put the parts in perspective and give the big picture is much appreciated. With so many sites out there, I can go anywhere for simple RAM benchmarks, but for me it is much harder to find informed discussions about why the part being reviewed is a good idea/choice or not. I really felt this side of the story was lacking in the X1800 reviews and am glad to see it here.
  • Houdani - Tuesday, October 11, 2005 - link

    Page 3:

    our overclocking clock frequency went up to DDR500 - 30 points higher.

    I think you meant DDR550.

    Page 4:
    In your table of memory, you list the 3 new sticks as 2x512. I think you meant 2x1024.
  • Wesley Fink - Tuesday, October 11, 2005 - link

    Corrected. Thanks for bringing these to us. It's funny that they looked just fine at 3AM :-)
  • Doormat - Tuesday, October 11, 2005 - link

    Whether its worth it or not to invest heavily (these pieces arent cheap) in DDR1 tech if you've already got a pair of fast running 2x512MB sticks. You'll just have to buy DDR2 sticks in a year if you want the fastest stuff (an A64 M2-socket based chip).
  • emilyek - Tuesday, October 11, 2005 - link

    Lame. Why not a big review on the many available 2 and 2.5 cas DDR 400 sticks? The Geil, Patriot, OCZ, Gskill, and Corsair already top out at about 1k FSB when loosed up, and the timings on these RAMS sucks anyway.
  • DrMrLordX - Tuesday, October 11, 2005 - link

    They've said it before, and I'll say it again: you just can't add every available DIMM variety to RAM tests. There's too much on the market, and many of the budget RAM types have wildly variable quality and performance.
  • RockSolid - Tuesday, October 11, 2005 - link

    The RamGuy link on Page 5 is incorrect.

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