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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  • walmartshopper - Wednesday, October 12, 2005 - link

    Thanks for the review. I've been toying around with 4 sticks of Ballistix pc3200, only to get them running at 480mhz with 2.5-3-3-8 2T timings (I got 530mhz with 2 sticks at 1T). It's not too bad, but after reading this, I decided to replace them with the 2x1024 OCZ pc4000. I actually have 5 sticks of Ballistix, and I'm hoping to sell them for 50$ each. Anyone interested?
  • AkumaX - Wednesday, October 12, 2005 - link

    I think on Page 2 when you were comparing 2T vs 1T you also meant 2x1024mb vs 4x512mb, rather than 2x512mb vs 4x512mb right?
  • cryptonomicon - Wednesday, October 12, 2005 - link

    no, he's comparing the same ram to show how the memory controller goes to crap after you load up more than two dimms. the sticks were both 512x2 plat rev II
  • TheInvincibleMustard - Wednesday, October 12, 2005 - link

    Nice, well-written article, Wesley. It seems slightly ironic to me, though, that this review comes out just as I'm expecting a 2GB kit from G.Skill via NewEgg to arrive tomorrow to replace my el-cheapo 2x512 (3-3-3-7 at DDR400? ick)

    Minor nit: pg 8
    "The performance differences will be that the NVIDIA 71.84 driver is a bit faster than the 61.77 and 71.84 drivers used in earlier memory reviews."
    Umm ... unless the driver is somehow faster than itself, I'm hoping that's a typo of sorts.

  • n7 - Wednesday, October 12, 2005 - link

    I'm glad to see a review on 2x1024 MB; it was past due.

    I realize there aren't many DDR433 & up 2x1024MB RAM manufacturers, but i would have liked to have seen Crucial, Mushkin, Patriot, Geil, since they all make good DDR400 kits, & at least in Mushkin & Crucial's case, they also make DDR433 & up kits.

    To make it simple, i'd like to see a review with a few more companies involved :)
  • rqle - Tuesday, October 11, 2005 - link

    Isnt it a little unfair to say one brand highest speed obtain @ 2-3-2-7 is lower then some other brand higest speed obtain is higher cause of 3-4-3-7? I mean, if you set corsair at a more lax timing AND higher voltage wouldnt it do better? Some one fill me in. Cause i remember back in the old days, memory i bought that can do 2-2-3-6 at 2.5v that was rated at 400DDR would overclock and do much better the same timing and voltage of some-old brand 533DDR+.
  • Wesley Fink - Tuesday, October 11, 2005 - link

    From p. 5 of the review:

    "Increasing voltage beyond 2.7V did not allow us to go any higher in overclocking, nor did more relaxed timings allow us to push higher. The limit is DDR492 - very close to DDR500."

    We tried to go higher but DDR492 is the limit with the 1GB Corsair dimms we tested. As we stated in the review it is likely Corsair is using a different Infineon chip than OCZ and Gigaram, or they are binning for best performance in the DDR400 to DDR500 range. Gigaram and OCZ are probably also using different Inineon memory chips - or they are at the least using different binning methodologies.
  • ozzimark - Tuesday, October 11, 2005 - link

    wow.. wesley, long needed article. however, some silly mistakes that i think i see :D
    first.. the gigaram oc'ing chart. max speed is put at 2-4-3-7.. are you sure it's not 3-4-3-7?
    also, the second speed is curiously 2-2.5-2.. where 2.5-3-2 is exepcted

    second, i know the difficulties of getting review samples, but where is the biggest name in 1gb sticks right now, crucial ballistix? i have seen many of these sticks do 280-300mhz.

    last, i remember the value ram overclocking article you guys had a while back. plan on going the same for 1gb sticks?
  • Wesley Fink - Tuesday, October 11, 2005 - link

    I went back to my test logs and corrected the misplaced values. DD436 is 2-3-2-7 and DDR556 is 3-4-3-7. The second value in all reported strings is RAS to CAS Delay in case anyone is confused by the notation.

    We hope to do a review of the Crucial Ballistix 1GB dimms in the near future. We haven't decided whether to do a Value 1GB roundup yet, but we will consider your suggestion.
  • Ender17 - Tuesday, October 11, 2005 - link


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