Moby ,,Check your memory settings,start with default and go from there,sometimes the voltage is either too low or too high ,and it is not the same with all mobo's...
I 'ave been 'aving the same symptoms here,and I KNOW it's not the OCZ 3500,so I reset the ram timings,problem gone...
Hope this 'elps,,,,,,,,,,,G'Luck..
What brand of memory did you use to test? I've heard Asus motherboards are very picky about OCZ RAM. So yeah, tweaking your settings could help. It really sounds like a RAM problem to me. You might try memtest to make absolutely sure the RAM isn't the problem.
However, if you havn't reinstalled your OS, you shouldn't even be looking at hardware problems.
The PSU is possible, but not likely with the problems you listed unless the trouble occurs only when your computer is under heavy load.
I guess it's a good thing that I adjusted the timing manually. I played around with the settings a lot with the previous RAM but just set it to auto when I installed this new batch. I actually had the settings a little conservatively so I corrected them and we'll see how it goes.
This type of issue is always so frustrating because it's make a change and maybe wait a few weeks.