Restart Issues?

I'm looking into putting a fresh copy of windows on my desktop but everytime I go to restart the display stops functioning. Right after restarting, once the computer shuts down and gets ready to restart, the power to the computer will be running (ie power is running fine to all parts fans, HDDd etc) but the display goes out and theres no way to get it running until I shut the computer down for ~15 mins. I switched power supplies from my 600W to a 500W and both seem to work fine so I'm running low on ideas.
Thanks