I slapped in the FX-55 and all was well for a week or so, untill lastnight. It kept rebooting on me, even at stock speeds. I swapped memory, memory slots..nope. I put back in my Opti 148 and same deal. I am on a fresh install of XP, like 2 weeks old. I am thinking PSU or Mobo...not much else it could be, right?