x7200 beeping/overheating

Can't think about a better title. What happens is, sometimes when the computer gets too hot, the fans would kick on max, then the speaker starts beeping, and after a short while the computer shuts off. I have i7 950 and 2 GTX 460m. I checked the temperature when it was beeping, CPU was around 70C, and graphic card is also 70+. It's hot, but the cooling should still handle it. Before you say it, yes I cleaned the computer.
Also a related problem: sometimes the graphic cards randomly overheat. It happened when I was playing Smite, a game that doesn't even need SLI 460m to get 60FPS. When I turn SLI on, however, in a few occasions, GPU 2 overheated to 100C. I thought it was a driver problem at first, but I tried a few different drivers from 2012 and 2013, and the problem still occurred. Maybe that's a hint I should get a new computer...

 

hmmm, those random temp spikes could point to an ill fitted heatsink maybe. check and see if all the heatsink screws are tight and covering the gpu core and vRAM properly.

or what about thermal paste, when was the last time u applied a fresh batch of it onto ur cpu and gpus?

 

Hopefully the thermal sensor is not faulty. It's worth physically inspecting for bad contact first, as jaybee suggested.

 

This happened to me and my thermal sensor was broken, I was pretty much using the wrong heatsink for the card that I was using.