Black Screen FTW!!!!

Hello evryone, There is my problem. This morning I was installing the 1.1 CoD5:WaW patch on my computer. When it was done installing it frooze so I rebooted my computer and then... Nothing loads not even the first screen that says XFX play hard. Its only a black screen. Ive tried unplugging my 8800gt cleanin the pci port. I also changed my Powersupply and cleaned my ram. It still doing it. HELP ME PLEASE!!!

Thank!

well it was the psu that was in my case before I used it like for a week then upgraded for a cheap 550W. I just installed my old 1 thats is a good 450W

EVGA 8800 GT 512 MB superclocked edition
XFX 650i Ultra
2G ram (corsair Value slelect) PC2-5300
80 GB hard drave
Psu= 450W model = Xion (came with the case)
DVD rom


2. Yes and Yes

And I also cleared CMOS... Nothing....