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I have a 2011 Macbook Pro 15" running Sierra.

The Macbook's fans are annoying me to no end - they are running most of the time I do serious work, right from the minute I start. It can get hot here in the summer, but it happens also at reasonable room temperatures, like right now, at 23°C (73°F).

Here's a graph of my CPU load over an extended period of time, looking fairly relaxed to my eyes:

enter image description here

yet the fan is running constantly:

enter image description here

This has been happening for the past three versions of OS X, so it's nothing version specific. (I started thinking that maybe this isn't normal only recently.)

Things I have tried:

  • Made sure there are no processes running in activity monitor that hog a lot of CPU time (my work tends to be CPU/GPU intensive though, Photoshop, IDEs, etc. open in parallel all the time)
  • Reset NVRAM and SMC, many times

  • Opened the device and removed a giant piece of lint from behind the air ducts (I was sure that'd fix it):

    enter image description here

    (I didn't do anything else in there other than remove the easily accessible, obvious blockage, though)

Is this normal? Is there anything I can do? Is there some unofficial way to get to the CPU, and maybe apply some better thermal paste? Is there some other potential bottleneck that I should look at other than CPU?

The machine is perfectly usable for me otherwise despite its age (after a RAM and SSD upgrade).

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3 Answers 3

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You need to strip & clean the entire airflow, if that fluff-ball was clogged in the outlet, there's an entire duvet inside. All the machines here get a full strip & clean once a year, with a 'quick blow round' in between. If it's gone 6 years without cleaning, it's likely to be pretty well-insulated in there by now.

iFixit teardowns are second to none - there is far too much for me to try to précis here
iFixit - MacBook Pro 15" Unibody Early 2011 Teardown

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    Yup - this did wonders. Opened it again, cleaned the fans themselves (they had a crispy crust of dust that I had to actually scratch off with a screwdriver) and blew through the ducts with one of those compressed air cans. The fans run much more silently now and at about 2000 RPM less than they did before at comparable CPU temps.
    – Pekka
    Jan 29, 2017 at 15:46
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Open Activity Monitor and take screen shots of the full window to share with us. I'd like to see the CPU tab, sorted by % CPU with the arrow pointing down; and the ENERGY tab, sorted by Avg Energy Impact with the arrow pointing down.

These can help us find out if you have a run-away app or process.

After taking those screenshots, I'd advise performing a Safe Boot. Give it a few minutes of runtime, long enough for you to determine if it's better in Safe Boot or not, then restart to get back out of Safe Boot.

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I have a Macbook Pro 15" Late 2011 and I did this:

Assuming your heatsink and air chamber is free of dust, cleaning the 2 Sunion fans is key, specifically their fan blades. I went from 6000-6200 rpm to 4000-4500 rpm with 25% cpu usage.

  1. Disassemble each fan into its 2 metal plates by removing 2 small phillips screws and the electrical tape holding the fan wire. Place tape elsewhere on a table so it does not stick to dust and cotton fibres.
  2. Use a tooth pick and a tiny little cotton ball (from a q-tip) and wedge it deep between every fan blade to remove the caked on dust. Give it a good scrub.
  3. Caked on dust won't go away with a simple air compressor can, you need cotton ball friction to remove it
  4. Remove any stray cotton q-tip fibres around the fan assembly, they might start a fire since cotton is flammable

Air friction from the dust on each fan blade is a major debuff to the airflow, causing your fans to spin faster and louder to compensate.

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