I post a couple days ago and didn't really get much of a response. I have a 256MB Radeon card that just one day decided not to work. I put it in a couple days ago and it worked fine for about 5 hours...then it just died again. When I start my computer it just has a black screen and my monitor goes to sleep. It shouldn't be my power supply. I have a new 500watt Ultra X-Connect...not really sure what the problem is. I really need some help.