Yesterday I installed a Gigabyte Rocket 3D Pro sumthing cooler on my brothers P4 2.8 computer which works pretty well. But today I found that whenever an application like a game or 3D Mark 03 is opened (while the pc is still loading) the pc reboots itself. When it hits windows again it says sumthing about a fatal error. So from there I thought maybe a corrupt HDD or PSU. I had a utility installed called PC Mechanic 5, So I ran the program (luckily the pc didnt reboot) and I started using the options on the program to clean junk files, fix errors, clean registry etc. After all that it had a degrag option, so it started running ( The Defrag took about +-2Hrs) and when I arrived back at the pc, the screen was blank. The monitor was still on but no picture, I tried everything I could and eventually turned off the pc. When trying to turn it back on, it still doesnt give a picture on the screen. What could be wrong? Could it be that the HDD is now damaged and cannot load ?? Maybe the PSU damaged ??