I suppose it could the the PSU but it wouldn't be my first guess. If it's the Silverstone in your sig, then I'd suspect it even less. Memtest is a good first test because it only takes a few seconds to boot (when it works. ). Prime95 "blend" is the best there is for testing memory. Like I said earlier though, you may have to use "custom" and tweak the total memory used so you don't swap.