So I was playing bf3 on pc on normal quality after about 15 mins my pc totally shuts down, now this has never happened so I let it cool down for about an hour and turned it back on. but on my monitor nothing shows up. I have a Vapor - X Radeon 6770HD what does this mean. all of my other components are working. my gpu has a led on it not extra and it's not turning on???? what does it mean??