I bought a used desktop computer yesterday off Craigslist. Right after I got the computer I decided to format the hard drive and reinstall windows. As it was installing windows, the computer turned off for no reason, but I thought that I might have nudged the power cable. After I rebooted it seemed fine and installed. Then once I got into windows, it turned off again. I still figured that I had nudged the power cable so I restarted and it worked. After about fifteen minutes, the computer shut down again. However, this time when I tried to turn it back on it would not power up, except for a second and then shut down. I opened up the case to see if there was some short circuiting going on and then removed the power from each of the components one by one to test it. When I remove the power connection from the hard drive, the computer boots up. I even got Ubuntu to run live. So the problem is definitely in the power connection to the hard drive. Can you explain this and tell me how to go about fixing it? I used it for literally under an hour before it started shutting off and giving me these problems. The hard drive is a modern seagate baracuda 7200. It is important to note that it has some kind of power converter set up, since it only accepts "serial ATA" power. Maybe this is the heart of the problem?