Build issue/crash please help!!! Crash in prime95 and other stuff

Well I just finished my first build, but have been having an extremely frustrating problem. I've asked elsewhere and have had no luck. I joined here after seeing a lot of knowledgeable posts to issues. I'll just list what I have done/know.

The crash looks like this.

http://go.overclockers.com/?id=1132X509988&url=http%3A%...

here's the build:

Gigabyte GA-MA785GMT-UD2H
Corsair CMPSU-400CX
AMD Phenom x2 555
Cooler Master elite 341 case
Cooler Master Hyper 212+ HSF w/ AS5
one module from this kit http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Windows 7 64 bit
one extra 120mm fan for the front of case


1.prime95 medium test, crash at beginning of test

test 2, 4000 lucas-lehmer iterations m19922943 using fft length 1024k

2. prime95 light test runs fine, temps fine

3. crash once in memtest, hasn't since

4. errors during test 5 of memtest86, not since. I might run this again to make sure. also the test stopped or it froze since esc did nothing.

5. exchanged board, same issue with new one.

6. no overclocking, everything is at stock right now.

7. updated bios, no luck.

Can someone please help... This has been extremely annoying since this is my first full build.

Someone mentioned something about vcore and that to match the vcore in cpu-z in the bios. Can that help and how do I do it?

Can the ram still be bad, I bought it used and contacted the seller. Obviously he doesn't want it to be bad so he has been assisting me in solving the issue with no luck. But he said if the ram is bad he would refund me as long as I can prove it somehow. I already sent a screenshot of memtest86 errors, but he was convinced it could have been caused by something else. I dont have any other ram to test.

I am hoping it is a bios setting issue and is just a product of it being a fresh build.