I ran MemTest and it "crashed" after 10 min or so. All the characters on the screen were turned to solid white blocks and I couldn't go anywhere from there. I pulled out my 256 stick to test the 512 alone, and MemTest ran for over an hour, but then it just froze. It didn't show any errors up to that point, but it wasn't finished testing.
According to motherboard monitor my CPU might be in danger. The default CPU temp alarm went off immediately. The temp was at 161 F (around 75 C) which was beyond the default 158 F (70 C) alarm.
I dont know if it means anything, but I noticed that my fan speeds were 1679 RPM and 3183.
Also, a few times now the system has turned itself back on for no reason. It'll crash and I'll hold down the power button until its off, but sometimes it'll come back on a few minutes later without me touching anything. The thing is off; the fans aren't moving, nor is anything else internal, and the light on my monitor is red. Which makes me think something could be wrong with the power supply...
I'm pretty noob when it comes to hardware, but it seems like somethings wrong with the power supply and/or the CPU fan+heatsink. The only reason I haven't tried replacing them is because I don't have a lot of money to throw around.