My PC has recently been crashing randomly, it can only make it to past the desktop for less than two minutes. It's running Windows 7 64-bit Ultimate after an upgrade from Professional x64. I have had many OS's on this machine and many upgrades, but I can't trouble shoot this problem. First, it seemed to be fine and I had downgraded to Windows XP x64 and was ready to install 7. The system ran flawless in medium/high gaming on a 2.66 GHz C2D E6700, 4GB (2x2GB) OCZ 800 MHz DDR2 Dual-channel, MSI GT 240 (overclocked), a WD 250GB (OS), 1TB Seagate (Data), 250GB Hitachi external, 2TB WD Element external, a 570 watt PSU, DVD-RW DL, and a Dell XPS 410 MoBo and case. I wanted DX10+support so I upgraded to Windows 7 Pro x64 and it was great. But about 2 montths later I began experiencing random crashes and tried to troubleshoot the problem but found no answer. I'm 17 and I'm in the York County School of Technology for Electronic and Computer Repair Technologies so I know my way around a PC, I had no problem wiping my PC as I always makes a disk images every month or so. I formatted the drive and upgraded from Professional to Ultimate, after a clean install I added my antivirus and firewall, Comodo Internet Security Suite, and updated windows. Next I installed drivers, NVidia just put up beta drivers for the GT 240 so I installed that, next was audio and finished. I rebooted, logged on, installed bittorrent and a few other programs I've used for a while then it locked up. I rebooted logged on and a few minutes later it froze (please notice I had no BSOD, mouse and keyboard wouldn't work) so I remembered the beta drivers for my video card, I booted to safe-mode and uninstalled then reinstalled the last stable release. I booted up, logged on and a few minutes later locked up. I reformatted one last time but upon installing I noticed my drives were not available (except C:), I checked the BIOS and only SATA 0 and 1 detected a drive. I switched the data drive through all of the SATA ports and nothing, then I replaced it with the boot drive and it didn't detect the SATA 2-6 I found out. I replaced the boot drive and reinstalled Windows, it took 17 hours to finish when it usually takes 30-45. Now could this mean the SATA controller may be shot or PSU? Please help me on this as I have invested a lot of time and money on this PC.