P5B killing my Ram?

[Gree]

Ok, I'm still quite noobish here. I bought a vanilla P5B with E6400 Conroe and (foolishly) cheapass DDR2 PC6400 1 gig ramstick. It worked fine for a few days then began crashing the computer. Memtest showed flooded with errors. I returned the Ram thinking it incompatible and the guy in the shop changed it for some ram by a company called elixir (same specs) he assured me he had sold with many p5b boards without issue. Memtest showed it was fine. Now 2 days later, crashing again and memtest shows errors.
My question, can ram start good and go bad so quickly twice with two separate brands or does the board kill ram that isn't to its likeing even though it works perfectly for a few days?
Kind of pulling my hair out in my ignorance.

 

[Gree]

anyone. My computer is currently an expensive paperweight. I want to buy some new ram but dont want to fry it too.

 

[SunnyD]

Are you overclocking? If so, are you overvolting the memory? If not, is your board overvolting the memory anyway?

 

[Gree]

I'm running at the default bios setting of 1.9v
Funny, memtest was showing errors then after about 10 bios changes and reboots with bios back to default, memtest showed no errors and the computer booted fine for a few days and sure enough started to crash again after that and memtest went back to errors.
At least I know the memory is not fried. Something makes the memory mysteriously go bad and come good after intervals of several days it seems.
Any ideas? The motherboard doesnt seem to be getting hot and the case is like a wind tunnel with the amount of fans running air through it.