Unstable 1066mhz when running 4 dimms gigabyte

Hi all - first time poster. Looking for some answers.

I've been trying to run 4 sticks of 2GB memory at 1066mhz, but have been experiencing OS lockups at POST, errors in memory tests (MemTest86+ 4.10), and occassionally the inability to boot altogether (no POST). Running at 1066mhz with either set (2x2GB) works fine with no problems after hours of memory testing or OS use, but when the two sets are used together, the system becomes unstable. All four dimms run stable without issue at 800mhz.

I'm hoping that it's just a matter of divining the right memory timings, but it could be that my board just doesn't cut it, or the fact I'm using memory from different manufacturers. Probably all of the above.

Another discussion seems to indicate it's an issue with AMD chipset, although the link they refer to appears to be stale:

My system and notes below:

GA-MA78GPM-DS2H (rev. 1.x)
- BIOS flashed to F6H
- stock settings except for changing memory speed to 1066mhz

AMD Phenom II 1045T
-stock settings

2x2GB Kingston - HyperX/Genesis - KHX8500D2K2/4G
- CPU-Z and other utilites shows SPD with JEDEC #3 settings up to 400mhz (nothing for 533mhz)....is my OCZ kit better in this respect?
- specs in PDF at above link reports 5-5-5-15 @ 2.2V (I think my mobo can only overvolt up to 2.1V)
- tRFC of 127.5ns

2x2GB OCZ - Reaper HPC - OCZ2RPR10662G
- Old non-nickel plated HPC version (likely not important, but ya never know)
- CPU-Z and other utilites shows SPD has an EPP setting for operating at 533mhz 5-5-5-15 @ 2.1V
- tRFC of 195ns

So, am I just out of luck? It's not critical that I run at 1066mhz, but if there's a way of getting there that doesn't require massive amounts of tweaking, then I'll go for it. I'll entertain advice on newer/better AM3 compatible boards, but I'll likely stick to what I have.

Any advice would be appreciated.

6 answers Last reply
More about unstable 1066mhz running dimms gigabyte
  1. The thing with trying to run sets of ram from two different manufacturers is that there is no guarentee that they will work together even though they have the same speed and timings. I would say that if you got a second set of the Kingston that matched the one you have then they would both work together with no problems but when you mix and match your asking for trouble.
    A lot of times people have success with mixing brands but there are those that do not.
    Since the Kingston ram is rated at 5-5-5-15 and 2.2v and you think that your board will only go to 2.1v then I would change the 15 to 16 or 17 and try to run 5-5-5-16 at the 2.1v or change the settings for both to run at 5-5-5-18 at 1.8v.
  2. Thanks inzone. Yeah, I thought that would be a potential issue, but since I couldn't get my hands on another OCZ Reaper kit, I had to look elsewhere.

    I think I tried 5-5-5-18 at 1.8V, but if memory serves, it didn't even get to POST. Basically, I've been trying to figure out if there's some lowest common denominator setting that both sets of dimms will allow for stable operation. So far, no luck.

    I should've looked more closely at the Kingston specs before purchasing...the 2.2V requirement for the higher timings likely lessens my chances of hitting 1066mhz with my current setup. I found it interesting that the newer Kingston parts didn't have the same EPP setting programmed into its SPD like my older OCZ part. Lesson learned.

    I'll keep at it...thx.
  3. I do think that the right combination of timmings and voltage will eventually get you there. If you haven't already you should keep a log so your not doing double work.
  4. Are there common "fail-safe" (but likely slow) settings to start with? I'm guessing there are dozens of guides. Is there a strategy you would suggest for the AMD-based motherboards? I'll swing through the forums for sticky notes, etc.

  5. I only use Intel systems and so that's what I'm familiar with but memory is memory and I don't think that there could be that much difference. To get ram running in a 'fail safe " mode you wouldease off the timmings and lower the speed an that would make it easier for the memory controller to use the mixmatched ram. Especially if there are real differences in the actual memory chisps being used, because of the different brands there can be big differences in the chips depending on where they are from and made.
  6. This problem has nothing to do with different memory vendors. I have 4 x 2GB Kingston HyperX memory on AMD board with 790X chipset and it has the same problem. I never found solution... not sure is anybody did...
    I have tried many different combinations of frequency and memory / chipset voltage.
    It seems to be problem with memory controller itself, I really dont know

    Edit: Due to AMD cpu architecture it is not possible to run 4 sticks of DDR2 RAMs at frequency of 1066MHz. Anyway this limitation is not present on motherboards of some vendors with latest bios update. More info can be found in this topic: http://forums.guru3d.com/showthread.php?t=283918
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