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.
Cheers,
Nathan
- 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.
Cheers,
Nathan
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