I've recently upgraded the hardware on one of my desktops (Motherboard, CPU & Ram) which required me to re install Windows Ultimate 7 (64 bit). The new install went flawless. All required drivers are installed, nothing in System settings indicates I have an issue with any device, etc. However, quite randomly the system crashes. Now, I'm not talking about a blue screen, freeze or lock-up. It's like the power was cut and she suddenly dies.. followed by a re-boot . I started looking at any and all hardware connections inside the box: CPU, faultly power connection somewhere, incorrectly attached CPU fan, etc.. I went back in, and everything seems okay. I re-installed again, this time formatted all drives, ensured the MBR was fine, went with only 1 hard drive.. bare minimums.. same issue.. sooner or later, I get the same crash. At least once per day. In an attempt to isolate the issue, I wanted to see if it was a hardware or OS/Software problem. I installed Linux Ubuntu. I had it running constantly for the better part of 5 days.. no crashes. At this point, I'm requesting outside help (this forum). any ideas?