My cpu temperature is always in the high 80's while at idle. When I start playing games the blue screen hits me and restarts the computer. When it's booting up, it won't let me past bios because it says the cpu is overheated and shows the temperature between 91c and 92c and never cools down until I turn off the pc.
I read some other posts stating it could be due to the thermal paste or the heatsink. I replaced the thermal paste several times (isopropyl for removing the paste) using the drop method, scraping it on with a card, using less thermal paste and none made the temperature go down. So I bought a heatsink with fan. Clipped it in and its reporting the same temperature. The heatsink is cold to the touch and is properly clipped in as much as it would go (the thermal paste transferred to the cpu when i take the heatsink off so I know it's clipped in right). I tried several programs such as Speedfan, hwmonitor, bios, etc and they are all reporting the same temperature although the core temperature at idle stay below 40c. Now I'm thinking it's due to the cpu or motherboard being defective. I bought these components 10 months ago and the cpu temperature recently just shot up to the high 80's.
I would visit an Intel and Asus forums to see if this is prevalent elsewhere. The CPU is still under warranty if you bought it new. The only way to troubleshoot this is to replace the CPU with one that is not acting up elsewhere. If it's not the CPU then the MB may have bad voltage regulation and be supplying too much voltage.
Whats your case? If you put it in an old hp compact I can see high temps being a problem. Is the temperature of your room high? That just adds to the base temperature of your machine that the CPU raises. etc....
But since it "just shot up" I don't think that the case is really the case, I'd go with what ram1009 and try to trouble shoot what part is defective. Test the cpu somewhere else and test the motherboard with a different cpu.
Also test the case with a different PSU (or your PSU on a different case/motherboard) if you can, something might have fried that kept back the heat it produced before, and such.