I've replaced the motherboard and powersupply so far. I've used HDTUNE and chkdsk on both harddrives in the system, I've ran Prime95 for 48 hours, memtest86 for an hour, and no errors at all. However during normal usage the computer randomly reboots. I can't reproduce the issue, however when I put the system back into production it will reboot randomly for whomever is using it. Any other ideas on what it could be? Could a bad video card cause random reboots? What is a good temperature reading utility? This is a Dell Precision 390.