I have an old GTX 770 that is broken and I don't know how to fix the problem. First of all, the problem is definitely this GPU and nothing else. My PC works fine with my 970, it only crashes with the 770. I can get to the desktop just fine, but after about 3 minutes of playing a game, the screen goes dark and doesn't come back. The GPU has never been overclocked past default factory settings. I have no idea how to fix this problem. Help?