CPU overheating and switches off before POST

[Kahnovitch]

Hi guys I’ll cut straight to the problem;
My cpu overheats within seconds of switching on. I mean literally seconds and then shuts down. The “cpu oveheat warning” beep (I set it up in the bios a while back) comes on the same time as the first post beep and the pc switches off.
I was having some overheating problems before so I bought a new 700watt psu, new fan and heatsink (arctic freezer xtreme) and have applied new artic silver 5 thermal paste after using two articlean solutions to clean the hs and cpu beforehand.
I’ve cleaned, reapplied and reseated the cpu about 4 times now and nothing has improved the situation.
Along with 4 case fans, optimized for good air-flow my rig is as follows..

Mobo: Gigabyte M61PME-S2 mobo
CPU: AMD Athlon 64X2 4200 2.2GHz
RAM: 2x1gig 6400 DDR2 kingston/crucial ram (cant remember which)
Gfx: Radeon ATI 512M 3850 pci-express
HSF: Arctic freezer xtreme fan and heatsink
PSU: Arctic Power 700W PSU

I’ve had this pc for about 2 years and in the last few months the heating became enough of a problem for me to purchase the new 700W psu, hsf and several tubes of artic silver and mx4 (I’ve tried both with no change in result).
I’m beginning to think my CPU is faulty as I have tried just about everything I can think of to solve the overheating problem.
Any advice would be appreciated as I’m at my wits end.

[uethello]

This sounds like a CPU internal problem, although this is one of the CPUs with the integrated heat spreader, so... as a last resort, if you have no warranty, and have decided to trash/replace the CPU, try removing the heat spreader. The heat spreader should not be soldered or epoxied in place, as long as you're careful not to shove the tool you use to pry it up into the cpu inside you should be fine. Then you just spread the AS on the actual CPU. This should lower your temps, unless it is actually something inside the chip shorting out, then you are out of luck and need a new chip. The up side is that if you do a straight replacement for this CPU watching the forums to replace it, it should be pretty cheap.

[Kahnovitch]

I took off the heat spreader and cleaned up the underside. I couldn't get the hsf directly onto the cpu so I applied some new as5 to the chip, replaced the heat spreader, reseated the cpu and hsf and the pc booted up!
It hasn't overheated yet after about 4 hours so thanks for the tip uethello.
This is probably just a temporary solution as the only thing pinning the spreader in place is the hsf, but considering I was about to bin the thing, I can't complain