Strange Thermal Issue with Used Laptop

[GutCruncher]

I have a used HP ProBook 655 G1.

I noticed at times when it gets busy (like I start a game or something). The fan Revs up eventually all the way after only like 30 seconds.

The strange part is this:

Air DOES come out the vent, but it is cool air UNTIL I hear something actuate inside. Like a short "pfft-click" and SUDDENLY the air from the exhaust goes from cool to hot. A few seconds after this happens the fan calms down and everything continues as normal.

There have been a couple times that the "click" sound didn't happen quick enough and it shut down (im guessing from thermal protection).
However, If I DO hear the "click" then I can use the system indefinitely without issue.


I opened it up and applied some new thermal grease to the apu just to be safe. I also ensure none of the intakes are blocked.

The heat-spreader has good contact (best that I can tell anyway). The fan is working, and since it spins faster as the temp goes up I'm guessing the thermal sensors are working properly as well...yes??? There simply seems to be no heat transfer to the exhaust until I hear that little sound.

Any insight into what is happening would be greatly appreciated.

 

[Fardringle]

Could be bad heat pipe(s). The fluid inside the pipes can bleed off or evaporate/solidify over time, especially if there's a crack or hole in the pipe. And once that happens, they cannot transfer the heat from the CPU to the heat sink/fan very well any more.

The "pfft" sound you are hearing might be the small amount of remaining fluid making contact with the hottest parts of the system and heating up very quickly (like putting water in a very hot pan and making it flash evaporate.

 

[GutCruncher]

ok. That seems to make sense. I'm actually surprised to see replacement heat pipes for this model are widely available and pretty cheap. I guess I'll change it out and hope for the best.

Thank you for your reply!!

 

[GutCruncher]

New heat pipe arrived today and I'm pretty sure it solved the problem.

Immediately upon startup I can feel warm air coming from vent. I've been running it a few hours and it seems to consistently work (as opposed to intermittently like before). I also no longer hear any sounds.

Thanks!

 

[Fardringle]

I'm glad to hear it! That was a fairly educated guess, based on the fact that I've seen it happen in several laptops here at work, but it was still only a guess. And I hate it when I guess wrong...