Memory Problems

I have been playing with my memory for several days now.

I have 4 x 1 gigs (I bought two of these
I also have an e6750 C2D

My C2D is running at 375 mhz (x8 for 3.0 ghz and it is stable prime95 for 24 hours, I have also tested at normal speed).
My RAM is at 750 mhz (spec is 800) and should run well at 4-4-4-12 however I am having some issues.

When I test the memory one stick at a time (in memtest86+ 2.11) for a full cycle I have no errors.
If I test them two at a time (single channel mode) same thing, no issue

but if I change to all 4 or 2 in dual channel mode then I get errors
not a lot of errors but a couple thousand in the 407 MB and 2802MB range.
it is weird because it will be a tight band (plus or minus 10 MB) were all the errors will occur.

I have lowered the timing to DDR-400 6-6-6-18 and I still get errors in dual channel mode.

I have also noticed that the Error-bit in memtest86 is always in one of two patterns (87000000 or 01000000).

two of the sticks do have errors but only rarely, see third post for more info

My second unrelated question is:
The memory says it should be run at 2.2V but I can not get it to be stable if I raise it above 1.8 any ideas what that is about?
4 answers Last reply
More about memory problems
  1. Some boards won't run ram stable with all 4 slots filled. You are doing the right adjustments to improve stability. If each stick passes memtest one at a time, the problem isn't with the ram, but the motherboard chipset. You can try changing the memory mapping setting if it's an option. Good luck.
  2. I have narrowed the problem down farther.
    Two of my memory modules will occasionally have errors in memtest86.

    If I let one of them run for several hours it will get 2 errors (never in the same spot) every second or third cycle.
    The other stick of RAM will be fine but when it gets errors (maybe every thind cycle) it will have several hundred errors at a time.

    what is up?
    why not every cycle
    is it a timing issue?
    if I slow them down will it solve this?
    how difficult is it to warranty replace crucial RAM?
  3. Some folks have had similar issues. When I had an old asrock dual sata II board, it never ran perfect with all slots filled. I got a bluescreen about once a day (per 2-3 hours usage). Crucial will honor their warranty. Use just the good sticks while you send the others in for replacement. Request the rma online, and find your original invoice if possible. I can't predict if new crucial ram will fix your problem. I suggest you contact your motherboard manufacturer or look for tested ram modules on their website. You should have no trouble selling the crucial if you want to try a different brand.
  4. I would run the ram at the motherboard "auto" or spd settings with memory mapping enabled for awhile. If it runs smoother, don't worry about setting the ram to the recommended specs. 1.8 is ok for voltage, and the ram will run cooler at the lower setting. You won't notice enough difference for all the hassles of returning the ram or switching brands, but it's your call.
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