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CPU temp 100°C+, fan still at 2000RPM

T

Transporteur

macrumors 68030
Original poster
Nov 30, 2008
2,729
3
UK
Hey there
I've notices a really strange behaviour with my 13" MBP. The fan simply doesn't go faster on high loads, which results in a CPU temperature that is far beyond the operation specification Intel provides.

Seems as if the SMC controller is kind of broken. I tried to reset it, but that didn't change anything. A PRAM reset also didn't work.

How can I fix that?
 
100°C is deadly and far from standard! Keep in mind that the 100° are read from the heatsink, so you can probably add another 10-15° for the core temp. Intels maximum core operating temperature is somewhat around 90°C. With a proper cooling solution and normal ambient conditions, the chip should never go over that value as it reduces its lifetime dramatically.

When I got that machine the fan got to 5000RPM+ even at 70°C, so there is definitely an issue with the fan controller.
 
Transporteur said:
100°C is deadly and far from standard! Keep in mind that the 100° are read from the heatsink, so you can probably add another 10-15° for the core temp. Intels maximum core operating temperature is somewhat around 90°C. With a proper cooling solution and normal ambient conditions, the chip should never go over that value as it reduces its lifetime dramatically.

When I got that machine the fan got to 5000RPM+ even at 70°C, so there is definitely an issue with the fan controller.
Click to expand...
105° C for the P8400.

Are you waiting around for the fans to spin up? Be a little more patient. Apple doesn't want the fans spinning up from idle for a few seconds of heat.
 
Eidorian said:
105° C for the P8400.
Click to expand...


Higher than I remembered. :eek:

Eidorian said:
Are you waiting around for the fans to spin up? Be a little more patient. Apple doesn't want the fans spinning up from idle for a few seconds of heat.
Click to expand...

You are right Eidorian! I waited a little longer and finally, after 8 minutes, the fan spun up to 5000RPM.
Still the reported temperature was way too high, so I ended up re-installing iStat.
My temperatures are way lower now and the fan spins up at 70° again.

So the book was fine, only iStat reported false values.

Thank you very much Eidorian!
 
It's alright. I hope I wasn't too hard on you about this subject. It's a rather common one.

Software is going to poll the temperature sensors and you can even go down to the diode. There's a certain level of variance nonetheless. It's going to save itself if you're in real danger. You're also under warranty. ;)
 
I'm glad I was able to help you. Be glad that your experiences and this thread are going to help the next person that asks this question.
 
Transporteur said:
100°C is deadly and far from standard! Keep in mind that the 100° are read from the heatsink, so you can probably add another 10-15° for the core temp. Intels maximum core operating temperature is somewhat around 90°C. With a proper cooling solution and normal ambient conditions, the chip should never go over that value as it reduces its lifetime dramatically.

When I got that machine the fan got to 5000RPM+ even at 70°C, so there is definitely an issue with the fan controller.
Click to expand...

It reads the diode temperature, not the heatsink. Big difference there.
 
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