Impact of Athlon 64 Memory Controllers on 1GB DIMM Performance

While there has been a lot of talk about the different capabilities of the evolving Athlon 64 on-processor memory controllers, there really hasn't been much discussion of the limitations of some of the earlier Clawhammer controllers. We ran into this issue head-on in our first efforts at testing these 1GB DIMMs.

Most are aware that the early Clawhammer controllers did not officially support 4 DIMMs of any kind at other than a 2T Command Rate. In fact, this continued on in the current Rev. E controller. Some are also aware that the Clawhammer memory controller did not officially support DDR400 with 4 DS DIMMs - official support was DDR333. However, most board makers found that the controller really had no problem with 4DS DIMMs running at DDR400 and supported that "extended feature" in BIOS.

There are not the only differences in the memory controllers that come into play with the more demanding 1GB DIMMs. Our standard test bed CPU has been the 4000+, specifically the original Clawhammer version. Today, you can also buy a 90nm Rev. E version, but we had found no reason to upgrade from the Clawhammer version - until these 1GB tests. Our first efforts with the OCZ 2GB kit saw things very much out of the ordinary in our memory testing. First, Super Pi was no longer a reliable indicator of top speed. In the past, we could run Super Pi, and if it ran, we were confident that the rest of our memory test suite would run without problems.

Now, with the 1GB DIMMs and Clawhammer controller, Super Pi could run perfectly at a CPU clock some 15 points higher than what we could get Quake3, or Return to Wolfenstein to run. With 1GB DIMMs, gaming was now the most demanding task in our suite.

The other strange behavior with our Clawhammer was overclocking. Our first efforts with the OCZ 1GB DIMMs topped out at DDR520. That seemed OK until we saw others doing 540 and even higher on simple air cooling with the same memory. What was different? We finally realized that the highest overclockers with 1GB DIMMs were using processors with Rev. E memory controllers.

Once we switched to an FX57, with a set multiplier of 12X to produce comparable results to past memory reviews, our overclocking clock frequency went up to DDR550 - 30 points higher. The Super Pi issue remained, since we could run Super Pi and Sandra Memory tests all day at DDR565, but gaming tests crashed the system at any setting over DDR550.

It is clear that 1GB DIMMs put a much greater demand on system resources than 512MB DIMMs. It is also clear that the newer Athlon 64 memory controllers are better at meeting the demands of 1GB DIMMs in overclocking. We went back and compared performance of 512MB DIMMs on Clawhammer and Rev. E just for a sanity check. There was virtually no difference in 512MB overclocking on either memory controller - pointing again to the extra demands of 1GB memory modules.

Our advice is to use a recent processor and memory controller with 1GB DIMMs if you plan to overclock the memory. If this is not possible, then expect lower overclocks from your 1GB DIMMs.

Why 1GB DIMMs? Performance Test Configuration


View All Comments

  • woodspire - Thursday, June 29, 2006 - link

    What happen if instead of using 4x 512 memory you use 2 x 512 and 2 x 1024. Same speed (PC-3200), same timing, and even same brand.

    Still acheving dual channel ?
  • qquizz - Saturday, December 10, 2005 - link

    Sounds great and all but a query at Pricewatch brought up a blank.
    Where can you buy the OCZ PC4000 EB Platinum Edition
  • Hurricanesan - Friday, November 11, 2005 - link

    I'm looking for 2Gb memories for my new computer.
    I had an hard time choosing between the Corsair 3500LLPro and the OCZ 1024MB EB Platinum.
    This morning, I've noticed this test. Since the OCZ was able to go up to 500Mhz and I plan using an A8N32-SLI, the choice looked easy.
    But a friend of mine pointed out an old story in which OCZ was giving very good sample to the press and lesser products in the shops. I've looked about that story and now it seems to me that OCZ is really unstable in its production and not very clean ... or used to be.

    I would really not like to buy those memories and find that they can't stand their specification.

    Since right now it seems that both the Corsair and the OCZ are not available in stores less that 2 hours plane from me, I have a week to make up my mind.

    If anyone can help me balance one way or the other, please post.

  • KriegsMaschine - Tuesday, November 29, 2005 - link

    OCZ is the best brand I'd say. I currently have Corsair Twinx C2Pro "2x512 ddr400 Cas 2.5" and it's good... but WAY TOO expensive for it's quality. You pay too much for the brand like you would by getting a cloth from a designer. OCZ have the best performance while having reasonable prices and quality stuff for Value, Mainstream and High-End. Their tech support is very good too, as all their products. My next PSU will be OCZ ModStream 450watts.

    Nice article. I was thinking these days about going from 2x512 to 4x512 with my Athlon64 since it's less expensive than 2x1Gb and generaly have better timing but after reading that 1T Command was impossible with 4 DIMMS... I changed idea!

    What would had been nice for the review would had been some more real game benchmarks. I mean not old stuff like Quake 3 because who care to have +20fps when you already got 550! Some newer stuff such as UT2003, FEAR, BF2, FarCry, HL2 would had been a better choice. To me those SuperPi, SandraMark... means almost nothing. All I want when getting such expensive rams is more FPS in games. Comparing 2x1Gb in 1T Command vs 2x1Gb in 2T Command would had been better too because don't you think 2x512Mb vs 2x1Gb is unfair? 0_o
  • Shimmishim - Wednesday, October 12, 2005 - link

    what the heck? no 2x1 crucial ballistix? wow. i have a set that can do 290 mhz 1:1 with 3-3-3-7 timings and only 2.8 volts. Reply
  • leexgx - Saturday, November 5, 2005 - link

    do not think it was out then (or it was not sent to anandtech)

    i just got the Crucial 2GB DDR PC4000 Ballistix from overclockers and its less then £200 for this week only (norm £240) (got the A8N-SLI premium as well)

    i good to see that Ballistix stuff can do that

    i probley just set me X2 3800+ at 250 so me ram is doing the same (got it at 241 now on the cpu it norm runs at 200 so its an 410mhz oc {4600+ x2})
  • ricleo2 - Wednesday, October 12, 2005 - link

    After some recommendations from the forum here, I just got 2 sticks of GSKILL PC4000 at one gig apiece to replace my OCZ 2 sticks at 512 Megs apiece in my MSI K8N SLI PLATINUM. After comparing benchmarking results, before and after, it was not even close. RMA already approved from NEWEGG. Reply
  • phidjit - Wednesday, October 12, 2005 - link

    It's 1024, with 2-3-2-5 timings and runs at DDR433, it seems like it would have been a better comparison to the Corsair "CMX1024-3500LL PRO" (also 1024, DDR443, but 2-3-2-6 timings).

    Anyone seen benchmarks for the gigaram mach10000?

    It looks like it could be a bargin.

  • qquizz - Wednesday, October 12, 2005 - link

    These are the type of articles I come to AT to get. Thanks Wes. Reply
  • znir - Wednesday, October 12, 2005 - link

    Thanks for the information in the review. however, i think it would be good to see result of 4x512MB high performance sticks like the OCZ PC4000 VX. Reply

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