Could it still be bad if Memtest says its good?

[lash_larue]

I'm doing some overclocking and every pass I make with memtest at the settings I run says it is good but I still have prime95 errors (in place large FFT tests). I ask because prime may stop after 3 mins, 30 mins, or 3 hours. The other day it ran for 21hrs before I stopped it. Started it back up later and it crashed within 3 mins the first time, 30 mins the next and after those 2 crashes it had been running about 3 hours but hadn't crashed when I stopped it.

One day last week it crashed within 3 mins of starting it, then 7 mins, then 17 mins and then ran for over 7 hours until i stopped it. I know overclocking isn't guaranteed but the person I bought the processor from says it good for 4+ghz on air. I have tried a Biostar Tpower HP45 and now a DFI X38 T2RB.

I have tried 2 gigs of mushkin ram that had memtest errors out the box, 2 gigs of dominator 800mhz with no memtest errors, and now 8 gigs of dominator 1066 also with no memtest errors at the current settings.

I'm not really asking for help trying to overclock it because i'm beginning to think as random as the prime errors are it must obviously be the processor, but I wanted to see what everyone thought about the memory.

I'm running an antec 1000w PS, an e8400 and the ram and motherboards mentioned. i have even tried running the ram at a divider that keeps it at its spec'ed speed and it still has the random prime errors.

[Ste]

the easy thing to do is just throw different RAM in there, if the problem persists, than the memory is probably not the faulty item..

[BillParrish]

Possible but unlikely. But here is the thing.

Testing (if you think about it) is a very difficult thing. Memtest is testing the memory sticks mainly, but it is running a very small OS and simple video and while it does just by nature of using the cpu and MCH/northbridge to communicate with the memory somewhat tests that data path as well. However it is just mainly testing the memory for reading and writing the correct values.

Once you load windows everything changes. Bigger OS more video activity (goes through MCH/Northbridge) other processes running, God only know what flowing through the MCH/Nortbridge to the ICH/Southbridge etc. etc.

You must regard the system as a whole, you cannot test a section of it absolutely independent of the other sub-sections/systems. Well you could if you had a couple of million in dedicated test equipment.

Try upping the MCH/Northbridge voltage a notch (unless it is already kicked up to a high value.)

With 8GB and OCing too , good luck, you will probably need to send a couple of months playing with clock skew etc. if your bios supports it.

[larrymoencurly]

Try more memory tests. I had a pair of DDR2 sticks that would pass MemTest+ ver 1.7 and Gold Memory ver. 6.xx but would fail MemTest86 ver. 3.3 and Gold Memory ver. 5.07.