Whenever I try to play a game (they were fairly demanding) my screen would enter its "idle" state and my PC would become completely unresponsive and would need a manual shutdown. Sometimes after doing this my PC would go completely black and white on startup, run at 640x480, have black borders, and basically act as if there's no GPU plugged in. I usually resolve this issue but the main problem remains. I suspect it's GPU overheating (it sits at 57 degrees idle if that's bad) since I haven't cleaned out my PC in a long time. The GPU in question is a gtx970, about 3 years old now. Please help.