I installed a E-Geforce 8800GT video card it worked then said I had to restart my PC for it to work. I did and ever since it worked 1 time now everytime I plug in my monitor to the card i get a black screen , The fan is spinning and everything system starts up. But the screen stays black. I disabled my onbaord , tried even deleting it , nothing seems to work. I have 450 watt power supply , it's enough because the card did work before. And it requires atleast 400 watts. I've tried a lot of things and cannot find a solution , anyone that can please help?
Sounds like a driver problem. Go to safe mode and delete and install new driver. Your new driver must be 100% compatible with your operating system! For example if you have Windows 7 64-bit version you must have the corresponding graphic drivers for that Windows! Go to nvidia website and select your graphic card model, your operating system version and e.c.t. then download and install your new driver. Restart your computer. That will (probably) fix your problem.
And to be absolutely sure that it's not a power supply issue, give me your psu (full) brand/model name, and i will check it for compatibility.