I've had this problem with my computer. Every time i play a game my whole system crashes and blue lines come down the screen, it happens about 10 - 20 minutes into the game. Thing is this happened about 6 months ago, one day when it crashed i couldn't even turn it on so i went out and bought a new Motherboard, installed it and still wouldn't turn on so it wasn't the motherboard. Then as i was playing around with the wires it turned on (I had no idea what i done) and the computer worked for a few weeks until it happened again, this time i took out a stick of memory and it worked again. So i went happily playing games for about 5 months without issues when it happened again today while i was playing New Vegas. I don't know what it is, I'm starting to think it's the graphics card. I'm really not sure as it worked for 5 months after it wouldn't turn on.
I'm just confused at what it could be, It's definitely not my monitor. Should i go out and buy a new Video card?
I'm out of ideas and not a very hardware savvy guy.