Heat problems z60t

[yarrow]

I have a z60t (2511E6U) running Windows XP. Recently it has been frequently overheating to the point of shutting down. Or rather, it thinks it's overheating; when I touch it it never actually seems that warm to me, but I downloaded tpfancontrol and can now watch the cpu temperature climb into the 80s and 90s until the system shuts down abruptly. This happens whether the fan is on BIOS control, set to manual in tpfancontrol at top fan speed, or set to an aggressive set of smart control fan speeds. Or if tpfancontrol is not running at all, although then I can't watch the temperature climb. It also happens regardless of CPU usage - the system can be 98% idle (monitored by Process Explorer) and the temperature still climbs. It does not happen all the time - sometimes the temp will stay stable in the 50s or 60s, but sometimes it will do the rapid climb.

I opened it up and cleaned out the fan, which wasn't particularly dusty. The fan is definitely working - I can hear it.

Based on what I've read on this forum it seems like there are two possible next theories/next steps:

Theory 1: The fan isn't cooling the computer enough because the thermal bonding between the processer and the heatsink isn't working.
Solution: apply thermal paste ala http://steve.tokyorocketscience.org/?p=4
Objection (practical): I was scared enough when I opened my computer to clean the fan; I'd find it very alarming to try to smear goo on its parts
Objection (theoretical): Why does the temperature only do this rapid climb sometimes? Why doesn't the computer feel particularly hot? Maybe this isn't about real heat...


Theory 2: There is some kind of sensor problem whereby the temperature is getting misread
Solution: Upgrade BIOS (?? are there other possible solutions under this theory?)
Objection (practical): I've never upgraded the BIOS before. There are dire warnings on the Lenovo site about cutting power or shutting the system down in the middle of a BIOS upgrade. What happens if the thing overheats and turns itself off while I'm upgrading?
Objection (theoretical): Does it even make sense that this could be a software problem, or is the turning itself off phenomenon a function of the processor rather than the software? (Can you tell I have no idea what I'm talking about?)

Oh, and it's out of warranty and I'm a bit hesitant about just handing it over to a repair shop (though if you have recommendations in NYC, I'm open).

Sorry for the novel - anyone have any advice or votes as to best course of action?

[yarrow]

OK, in case this piques anyone's interest: it seems that the temperature spiking thing is happening only after the computer has returned from standby. If I restart the computer, the temp doesn't spike. If I close the lid and re-open it, it does. And this happens even when there is little or no cpu activity.

[rknotes]

I had similar issue and when I cleaned the fan.. which did have some dust.. it became much better.. I do notice overheating sometimes.. not as often as earlier..