Alright, so even if I leave the desktop in idle, it still does this. At first, I thought it was the power supply, but then, I took the side panel off of the PC, and started it up. I saw that the CPU, Power Supply, and Case fans were working fine. Then, for no reason, the case fan speeds up, and gets louder. Then after a few minutes, the whole thing shuts down. I am beginning to think it is a bad power supply. Please help!