David Shaw wrote:

> running under the PSU... could have been a cheap product, but I'm
> weary of pinpointing the problem too soon.

have you tried reseating the dimms?
cleaning the contacts with a soft cloth might help also.

if the RAM worked fine in the "gaming machine" configuration, I very 
much doubt it's faulty.  my tests with doom3 and mismatched memory dimms 
resulted in record speed very reliable "fault detection" (i.e., crashes 
and freezes after no more than a couple minutes) while windoze itself 
seemed to run fine for hours without any apparent problems.

mkb.