Hot computer and Loud Fans

My CoreDuo Macbook Pro was having similar problems with the CPU reaching 92C on Handbreake tasks. I cleaned the dust and crud from between the fans and Heat Sinks and got a 20C cooler machine. Disassembly is not for the faint hearted, but there are some good videos out there that show how many screws to remove and in what order

aard: That's all well and good for a machine that's out of warranty, but inadvisable for one that's still covered, as most unibody MBPs are. These machines run very hot when they're working hard, and if the fans speed up when the MBP reaches 80-90°C, then things are working as they should.

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There are a couple of things you can check if you are worried about this:

Open Activity Monitor (in the Utilities folder in your Applications folder) and check for any hung up process which might be running in the background and hogging the CPU. Be sure to select "All Processes" at the top and "CPU" on the bottom bar. Sometimes a process will hang up and hog the CPU, causing extra heat and fan activity.

Also, run the extended version of the Apple Hardware Test and see if anything shows up in the form of an error code.

When you say "hotter than usual", is there any new activity going on that's associated with the heat and fan speed? As eww said, if you are doing something processor intensive and the Mac gets hot and the fans speed up, that is exactly what is supposed to happen.

Good luck!

The comments from S.U. above are right on the money. I had a similar problem a couple of weeks ago... my machine was running hot with loud fans almost immediately on waking from sleep, every time I did it. I finally checked Activity Monitor and sure enough, there was something using up a huge portion of CPU. I shut that off, and everything went back to normal, and has been normal since.

This can sometimes be a problem for people like me who just sleep their computers and rarely power down. If something gets hung up, sleep doesn't always stop it from starting back up when you wake the computer. So, it's a good idea to check Activity Monitor or even restart as a first step to finding out why your fans are going full blast.

Not to mention pure BS. Cleaning out the fans and re-applying sane levels of thermal paste won't net you a 20 C reduction in heat. The chips run hot. 90-90 C is acceptable. The Core2Duo safe operating limit is 105 C (CoreDuos were 100 C). My 1st gen. MBP was reached a blistering 106 C. Re-applying thermal paste and making sure the fans are clean (as well as the inner chassis) dropped it down to 95-100 C.

However, if the CPU reaches a certain temperature, the machine will shutoff. They have mechanisms in place to protect the notebook in case of fan failure (or other potentially catastrophic occurrences).

William, cleaning fans reduced my MBP temperature about 30°C (>74°C to <43°C, CPU <5%). Dust was blocking maybe 30% of the heat sinks. The MBP is sensitive to dust. My environment is typical southern California household.

Cleaning fans is a delicate job, best left to an advanced technician, but it works on recent MBP, and no thermal paste is needed. I removed 8 bottom case screws and 6 fan screws, cleaned with tweezers and a small blower, and reassembled. See iFixit.com for repair guides.

Message was edited by: Lawrence Jones1