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Optimal settings for F3-12800CL7Q-8GBECO in DH67GD MB with Intel i7-2600K (DDR3-1333)

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  • Optimal settings for F3-12800CL7Q-8GBECO in DH67GD MB with Intel i7-2600K (DDR3-1333)

    Hi! I'm the proud and happy owner of the following brand spanking new setup:
    - Intel DH67GD motherboard
    - Intel Core i7-2600K CPU (aka "Sandy Bridge")
    - G.SKILL F3-12800CL7Q-8GBECO (4 x 2GB) memory

    So far, pretty sweet, but I'm trying to sort out BIOS timing to get the best, stable performance while maintaining 1.35V, which was the intent of buying these DIMMs. The DIMMs are rated at DDR3-1600 1.35V, but the CPU only runs 1066 or 1333. I have no plans to overclock, and this board/BIOS/chipset doesn't support that anyway -- but I do have pretty free control over DDR3 timing. I hoped that the SPDs would have an LV profile for 1333, but they don't.

    Here's are the knobs I have available in BIOS for DDR3 timing, and the BIOS defaults (in DDR3 cycles):
    tCL 9
    tRCD 9
    tRP 9
    tRAS 24
    tRFC 74
    tRRD 4
    tWR 15
    tWTR 5
    tRTP 5
    tRC 15
    tFAW 20
    cmd 2T
    volt 1.5V

    I got the SPD contents via CPU-Z and decoded the XMP 1600 profile by hand to get the actual timing requirements:
    tCL 8.75ns
    tRCD 10ns
    tRP 8.75ns
    tRAS 30ns
    tRFC 110ns
    tRRD 6ns
    tWR 15ns
    tWTR 7.5ns
    tRTP 7.5ns
    tRC 49.5ns
    tFAW 30ns

    From this, I calculated the 1333 equivalent of the XMP 1600 profile:
    tCL 6
    tRCD 7
    tRP 6
    tRAS 20
    tRFC 74
    tRRD 4
    tWR 10
    tWTR 5
    tRTP 5
    tRC 33 (note that this number is a lot bigger than BIOS default! not sure what to make of that)
    tFAW 20

    I didn't try it at 1.5V, but at 1.35V memtest started giving me errors pretty quick. Theoretically, it seems like this should work, except that the XMP profile is specified for 1DPC (DIMM per channel), and I'm running 2DPC, which will affect signal integrity. I bumped tCL up to 7, and it seems stable so far -- just passing 250% coverage on 6 threads of memtest, each covering 850MB, while I'm working on this post. So now I'm running 7-7-6-20 at 1.35V with the rest of the timings as shown directly above (1333 timings derived from requirements in the XMP 1600 profile).

    Comparing the default settings with my "optimized" settings does seem to show up to 15% improvement in PCMark Memory Mark, but I get enough variation in that test's results that I don't know how much stock to put in it.

    Anyway, I thought I'd post this here in case anyone is searching for data on how hard you might be able to run these in a 1333 system at 1.35V, since I couldn't find any info on that before I bought these on faith. Also for people who are looking for data on how well they work with the H67 (and presumably P67) chipset with Sandy Bridge. So far, so good.

    Finally, if GSKILL can make any comments on any of my settings, regarding whether or not they are reasonable, that would be much appreciated! I want to make sure this thing is as zippy as possible, but also rock solid.


  • #2
    Timings are precise, you may want to try a tad higher in DRAM Voltage to see how much til it can support CL6. Should not need much more, under 1.40V should do it. Set voltage may be slightly higher than actual voltage, so you may just need another level up so it can get a full 1.35V.

    Thank you


    • #3
      Thanks for the response! Unfortunately, I was not able to get it to run CL6 (with all other timings unchanged). I tried 1.40V (blue screen during boot), 1.45V (memtest errors right away), then 1.50V (memtest errors after running for a while). I didn't go any higher than that.

      So I'm back to 1.35V CL7 and everything is stable again. Hopefully this will help out other folks looking to use these DIMMs with Sandy Bridge.




      • #4
        Good info, appreciate your sharing it with us

        Pls offer comments on support I provide, HERE, in order to help me do a better job here: