CPU overheats in less than a minute

System:
CPU: AMD X2 4850e 45-watt dual core CPU
MB: Gigabyte GA-MA78GM-S2H rev 1.0
HSF: OCZ Vendetta 2


When I turn on my computer, the CPU temp rises until the computer turns itself off, which usually takes less than a minute. The temps of each core (according to CoreTemp) keep rising until they are both over 100C, at which point the computer shuts itself down. Readings from Hardware Monitor and Speedfan also show core and CPU temps over 100C, however HDD and System temps are normal (30's). This all started happening out of the blue (everything was fine one day, no hardware or software changes, then this started happening).

I thought maybe there was poor contact between the CPU and heatsink, or the heatsink had become damaged in some way. I checked the heatsink for damage or bad HSF-CPU contact (none, good contact), re-seated it twice with TIM, and made sure of good contact between the heatsink and CPU. However the CPU still overheats in less than a minute.

Also, when the temp readings are over 100C, the heatsink does not even feel warm to the touch, so I'm not sure if the CPU is actually overheating.

From the time when the computer worked fine to when it now quickly overheats, no changes of any kind were made. It just worked fine one day, and overheats in less than a minute the next.

Has the CPU possibly gone bad, or could the problem be the motherboard, or even the power supply?

Does the CPU cooler fan work?

try a differnet fan for your processor and check out to see if you can buy a different heatsink. Maybe on made for the processor. I have a dual core also and I had to get a different fan because im fans start slowing down cause my processor to overheat. you should read 30's- 40's for you processor, 50's
top. 60's you need a different strategy.

Intel Extreme 9000x 3.0Ghz @2 cores, 4GB 667Mhz Ram, 500GB @ 7200RPM +2-8800GTX SLI, 1920x1200. keep that stuff cool'd
3d mark 06 - 13k

Nothing changed from when it worked fine a few days ago, to when it now overheats in less than a minute. The voltage wasn't increased, and the fan on the Vendetta 2 heatsink works fine.

I thought maybe the contact between the HSF and CPU wasn't good, so I re-seated the Vendetta 2 twice with new TIM each time, but I keep getting the same results (drastic overheating, computer shuts down).

Would a problem like this point to a bad CPU, or something else (motherboard, power supply).

when you deseated the heatsink how did the tim look on the cpu was it thin like the heat sink was sitting all the way down or was it thick?

Only the CPU has the CPU temp sensors. Your problem is pretty clearly that the CPU cooler is not working properly. Either its fan is not working right or the heat sink itself is not working right (e.g. heat pipes leaked or came loose from sink). Every time you let your CPU heat up to the auto-shutdown point, you are damaging it. Replace the CPU cooler before you try running the system again.

Touching the CPU cooler tells you nothing, because you can't touch the cooler/CPU interface where the heat is being transferred. Trying another CPU cooler was a good idea; since that didn't work (assuming it has enough cooling capacity and was installed correctly), that points to the CPU itself or MB. To see if MB speed control of the CPU cooler fan is the problem, plug the CPU cooler's fan into a fan header other than the standard CPU FAN one. This should let the CPU cooler fan run at max speed continuously.
OTOH, if you've been overclocking the CPU, you might have damaged the CPU and that might be the problem. The way to test that is to try a different CPU.

Looks to me that the HSF installation went bad.

I basically agree with Mathos.

Things I'd try:

Lay the PC case on it side to even the weight pressure on the CPU. If the temps get cooler, that might be an indication the retention brack may be broken, or have a crack in it.

If the above is true, I'd take the MB out and check the back to see if the mounting retention bracket is broken from the back.