Powercolor 6950 1gig no longer displays

Hi.
I used to have a radeon 5770 prior to my upgrade which ran perfectly fine with no problems. Here is my history of what happened:

1. Upgraded to radeon 6950 1 gig with no problems. Uninstalled drivers correctly, did driver sweeper, everything was fine.
2. Random bsod while playing a game.
3. My monitor wouldn't be able to find the video card during windows load screen, so it would be blank, however once I got into windows 7 it would be fine and I could mess around.
4. Eventually after a few more crashes my computer boots up fine however the video card will start up and stop and repeat. (The fan spins up then slows down then speeds up then slows down etc.) with no display.

My computer is as follows;
AMD 955 BE phenom ii
hyperx ram (never had any ram issues prior, forget the specifics but it seems unimportant for this issue)
600w ocz power supply (modular xstream one?)
Powercolor radeon 6950 1 gig

My boot up is fine, i dont get any beeps of any sort. I have alot of LED's and my mice + keyboard have led's on them as well, i'm not sure if its my 600w not being efficient enough for the full load of everything? I don't know if "Bad" psu's mean they dont work at all, or dont work at the full 86% efficiency I see listed on sites. Any insight would be great. I would want to test on my old video card but I don't have it with me and can't use it until next week.

Your PSU should be sufficient unless it's faulty for that setup you've got. There are a number of things you could do:

1. Try putting that video card in a different computer and see if you have the same problems.

2. See if you get any problems when using safe mode in Windows.

3. Put old video card back in if you still have it and uninstall the drivers. Put the new card in and install the latest drivers from AMD. If that doesn't work then install the second latest drivers.

4. Set all the BIOS settings back to stock.

is your 6950 unlocked or stock?