How can I determine whether the heat sink is no longer firmly heat-tied to the CPU?

This appears to be the case for a seven year old MacBook, but I'd like to confirm without going to the trouble of re-applying the thermal paste just to find out that the old CPU (a core 2 duo) will indeed trigger the fan even for simple tasks.

I am looking for a recipe such as: Running a given process on a MacBook with a core 2 duo in a room with ambient temperature of 20C will not trigger the fans for at least 10 minutes.

In retrospect it's solvable. I can now run various jobs on each new MacBook and determine which processes trigger the fan. The same recipes should continue to work for the lifetime of a machine. If you have a core 2 duo and you can describe a specific testing recipe, please do.


Notwithstanding what Buscar says -

If you suspect the paste, change it.
For the sake of a fiver you'd then be certain.

I actually change the paste on all the graphics cards in the building every year, as part of a full strip & clean; though I only do the CPU coolers if I don't trust the existing application.
On non-Macs, cheap PCs, often the original paste is cheap & inefficient & simply changing it for good stuff can make a world of difference.

  • Probably good advice for someone comfortable tackling a task that ifixit classifies as "difficult". Also, the "try it and see" sounds like something to do with software. With hardware I'd like a more firm debugging recipe. – Calaf Mar 7 '15 at 19:48
  • I run on the rule of thumb… If I can hear the fans, it's time to clean them; while I'm there, the paste gets refreshed [on ATI cards you cannot get to the fins without splitting the GPU from the cooler, so I just had to learn the hard way ;-) – Tetsujin Mar 7 '15 at 20:12
  • But any benchmark stressing the CPU will trigger the fans, and most fans are quite loud, no? – Calaf Mar 7 '15 at 20:43
  • the fans don't 'trigger', they run constantly - at variable speed. If you run something like smcFanControl, you can check at what temperature they start to ramp up. My machine will happily keep the CPU temps at 42℃ or below, even in summer, under heavy load. Fans rarely get over 600 RPM. (Right now, 34℃ & 500rpm.) YMMV - I've not tested it on a laptop. – Tetsujin Mar 8 '15 at 8:05

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