Desperately Seeking Susan Synergy

In our opinion, the current acceptance of 64-bit Vista is going to create a large demand for 4GB memory kits. For these users, buying a 2X1GB may appear as a half solution - almost an illogical purchase considering Vista's voracious appetite for memory. As such, we know our work is cut out with this preview and subsequent review of high-end DDR3 kits. Testing niche products always represents a challenge because it is impossible to justify the miniscule gains in real world testing against the premiums one has to pay for that last 1% of performance. However, for a certain group of users, that last 1% means everything - cost be dammed. There is a demand for such products; in fact, this demand sometimes shapes the course and direction of future products. Therefore, we will simply say tongue in cheek, "It's a tough job, but somebody's gotta do it."

When we first learned that Corsair was sending us this $515 kit for testing, we had just finished pushing the ASUS P5E3 Premium to its limits and found it to be a fantastic board for overclocking 1GB memory modules well in excess of 2000MHz. In order to obtain these results we used 2X1GB modules from Cell Shock that are based upon Micron's D9JNL part. These particular modules scaled all the way to 2160MHz at CAS 8 on the ASUS board, although it has to be said it took a decent amount of work getting there. Very impressive of course, but it's also no real secret that few of us really run our PCs with such a setup, simply because the voltages and time required to reach such lofty speeds is more than excessive for 24/7 operation.

While the X48 chipset can achieve over 2100MHz with good DDR3, it does so at a real push needing more voltage to hold it'self together than most of us are prepared to use. The other logical choice for high-end DDR3 overclocking is the NVIDIA 790i chipset, but after significant testing, we realized it is no different. In fact, it's not nearly as stable when really pushed to the limit with these modules. Corsair's decision to quickly market a high-speed 2133MHz kit based on Samsung's new ICs certainly roused our curiosity. At the same time, we questioned how such kits would be qualified to run at stock specifications, never mind overclocking. Let's look at our first results.

Reaching DDR3-2133, the hard way
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  • hoohoo - Wednesday, September 10, 2008 - link

    I want bandwidth numbers!
  • geok1ng - Thursday, August 28, 2008 - link

    It would be good to see a table with CAS, Trd, dividers and frequencies for DDR3 users, just as you did for DDR2 users on the Rampage formula review">

    using the data from these tables i would infer that the best option for an E8600 and a high end DDR3 is:
    2:1 divider
    tRD of 5
    CPU at 10x400
    DDR3 1600
    These are the highest 12,5ns Trd timings displayed. Are they valid for a X48 DDR3 mobo?
    If they are possible at CAS 6, just how far can the FSB be increased while keeping the tRD at 5?
    What DDR3 modules are capable of reaching DDR3 1600+ at CAS 6 with the least voltage?

    on the Rampage review the authors proposed a DDR2 1000 CAS 4 solution as the best option for running four sticks of RAM, with DDR2 1200 CAS 5 as an alternative for 2 sticks of RAM.

    What are Anandtech suggestions for DDR3 builds on the X48 chipset?
  • Berger - Thursday, August 28, 2008 - link

    Aiming for a tRD of 6 at around 450FSB on the 2:1 divider brings the best overall balance for a 24/7 system. tRD 5 is attractive but you will lose out on copy and write bandwidth without sufficient FSB to bolster bandwidth. Plus the VMCH requirement is rather high for outright stability.

    For quad processors sticking around 400FSB is the best option, tRD 5 is likely to be too tight for some boards when armed with 4GB of memory.

    Personally I don't like suing 'down' dividers - ie anything that pits the FSB slower than the memory bus. Too many wasted clock cycles.


  • geok1ng - Sunday, August 31, 2008 - link

    So the problem is that for 10x450-a typical result for an E8600 at 1,4v- one can either run the memory at 2:1 and relaxed tRD and CAS or try slower memo speeds but tighter CAS and tRD. quoting the article i posted:
    "Moving on to the analysis at 450Mhz FSB, although we are able to show impressive memory read speeds at this same bus frequency using a 3:2 divider for DDR2-1350 CAS 5 at a tRD of 5, this configuration was far from stable on stock cooling alone - as was the memory speed. Most likely, the need to loosen tRD to 6 will be inevitable at this bus speed"

    So from your tests DDR3 based mobos didnt break the 1350Mhz barrier for tRD 5 operation?

    Is CAS 5,tRD 5 at the 1250-1350 range really that demanding on the NB?

    Is CAS 6,tRD 6 at 1800Mhz so much faster?

    What about CAS 5 tRD 6 operation at DDR3 1710 as in"> Sure the write and copy speeds are lower, but 45ns latency at "just" 1710Mhz is nothing to be ashamed of.
  • Berger - Thursday, August 28, 2008 - link

    *Edit* that should read using down dividers where the memory bus is running slower than the FSB. We don't have up didviders on DDR3 anyway. 2:1 is where the action is at on DDR3.

  • strikeback03 - Thursday, August 28, 2008 - link

    You sign as Raja here, as Berger in the NVIDIA comments, who are you?
  • nevbie - Thursday, August 28, 2008 - link

    Putting those BIOS screens into a gallery looks good - it's the first time I see this new gallery function used in an interesting way.

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