HP Pavilion shuts down with no warning

[Professor122559]

I have a HP Pavilion 6500 that has recently started shutting down for no reason. I have had it completely apart, cleaned and inspected every part. Everything looks good and when I put it back together it worked fine for about 6 hours then shut down again with no warning or error message. When I attempt to restart, it comes on for about 2 seconds and shuts off again. (On battery, battery w/adapter and adapter only) Even when it has sat overnight or for a couple of days and should be completely cool. Someone in another thread mentioned processor protection in the BIOS. How do I check that? Any help would be GREATLY appreciated.

 

[fastco]

Ram can go bad, i would do a thorough test on the ram.... I use the ultimate Boot CD. It's free and it has some pretty good tests on the cd.
http://www.ultimatebootcd.com/

 

[AlessBauer]

maybe It is strongly heated?

 

[Professor122559]

I have run the HP Health Check and everything comes back as good. It shut down again before I could run a directx diagnostic test on it. What do you mean by "Strongly Heated"? How do I check that?

 

[AlessBauer]

I Russian... English not perfect)
How much it warm up after long work(you write 6h)?
You do not use it on a blanket, a mattress?
after what ths start?

 

[Professor122559]

I had it sitting on a table. Plenty of ventilation. Even after sitting unplugged for a day and a half it still shut itself off immediately. It is completely cooled off but still will not start.

 

[AlessBauer]

Probably bad contact of the heat sink and hot unit (the processor, video the chip)
old thermal grease?