Originally Posted by arsenalbates
Update : I have been doing a bit of trial and error and notice two of the four ram modules were newer. I took these out leaving the original 2 x 256 modules and the computer has run for about 2 hours without failing. then I returned the new ram and took out the old ram and it started to power off again. unless it was coincidence I think that its the new Ram that is faulty (however it did pass a full memory test). the two matching pairs were at different frequencies, does this make a difference and could this have caused the problem ?
How long did you run the memtest86+ for that you are saying it was a full test? When I test RAM, unless it fails within the first hour or two, I typically let it run for 5-10 hours if I really want to thoroughly check for any and all errors.
Difference speeds do not matter. The higher speed modules will automatically clock down to run at the lower speed modules' setting. That shouldn't be the issue unless your motherboard isn't automatically handing that correctly, in which case you'll need to go into BIOS and set it manually to the specs of the lowest speed modules.