MacBook Pro (Early 2011) Underclocks CPU to 800 Mhz

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Level 1

8 points

MacBook Pro (Early 2011) Underclocks CPU to 800 Mhz

My MacBook Pro from early 2011 is underclocked at 800 Mhz per core (see screenshot below).

This started after I got a new logic board under the extended warranty for MacBooks from early 2011 with broken graphics. At the same time I installed a new battery as the old one had stopped working. Apple hardware test as well as the official Apple hardware tests run by certified repair shops return no errors (and thus the shops refuse to fix it).

I have tried every thing I could think of:

1) Resetting PRAM / SMC

2) Reinstalling MacOS (several versions - after repartitioning)

3) Installing Linux

4) Changing the battery

5) Changing the RAM

6) Getting the new logic board replaced

Nothing so far has made any changes. I'm getting really desperate now..

Any ideas?

Posted on Jul 7, 2015 2:14 PM

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Answer 1

Kappy

Level 10

361,741 points

Jul 7, 2015 2:19 PM in response to askielboe

If that is idle, then it is likely normal since the CPU throttles down when not in use. If you don't think that's the case:

Please make an appointment and take it in for service.

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Answer 2

SergZak

Level 6

10,338 points

Jul 7, 2015 2:30 PM in response to askielboe

Rest assured, there's nothing wrong with your MacBook as far as the CPU goes. I have a MacBook Pro (Late 2011) 2.8 GHz Intel Core i7 and running Intel Power Gadget (IPG) and just letting it sit idle produces the same results that you are seeing. Actually use the Mac (even just browse the web) with IPG running and you'll see the frequency rise and fall according to usage. If left idle, the CPU simply throttles down. Kappy is 100% correct.

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Answer 3

askielboe Author

Level 1

8 points

Jul 7, 2015 2:52 PM in response to Kappy

Thanks for the reply!

The thing is that even when utilizing the CPU 100% by running Geekbench (or other intensive tasks) the clock speed still hovers at 800 Mhz.

I get a Geekbench score which is a good 1/3 of what is normal for this type of machine (consistent with 1/3 * 2.4 Ghz = 800 Mhz).

I should perhaps also mention another symptom: kernel_task takes up a fair few CPU cycles. I'm not sure why this is happening, but I believe its merely a symptom of the underlying issue, as the CPU is also underclocked in Linux with no Apple kernel extensions running..

Edit:

pmset -g thermlog also reports CPU throtteling (CPU_Speed_Limit = 23). I've never seen such numbers on a healthy MacBook.

I have taken it to service several times and every time I have to argue with them for a long while because they claim nothing is wrong with the computer, because their apple hardware tests return no errors. I also spoke to a senior apple support person who basically told me that my MacBook was fine by definition because their hardware test said so and he didn't believe in Geekbench or Intel Power Gadget - as they are 3rd party apps not made by Apple.. So that seems to be another dead end.

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Answer 4

SergZak

Level 6

10,338 points

Jul 7, 2015 2:59 PM in response to askielboe

Maybe something is amiss with your MacBook after all. I just ran Geekbench (trial, 32-bit) with IPG running in the background and CPU went from about 800mhz at idle to over 3Ghz under full Geekbench load.

I would take the MacBook back to the Apple Store with ALL required benchmark software installed and actually show them the issue you are having. If you've already done so and they don't believe you, nor Geekbench, nor IPG, I don't know what else you can do.

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Answer 5

Jul 24, 2016 11:51 PM in response to askielboe

Did you ever solve what caused this? I think I'm having the same problem! ...

Macbook Air CPU throttled, flatlined at .80 GHz???

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Answer 6

askielboe Author

Level 1

8 points

Jul 25, 2016 12:54 AM in response to metroline

I did end up solving it. Turns out it was a power issue after all. I had replaced the original battery using one from iFixit. Apparently the iFixit battery had some issues (although I couldn't tell from the System Profiler, or anywhere else). And it was causing the MacBook to under clock the CPU. Whatever I tried (installing linux, and various command line utilities) I couldn't get it to clock it at the full speed.

I finally ended up getting another battery replacement from a certified Apple repair shop, and that fixed all the issues I had.

Hope this helps you. Good luck!

Edit: By the way, the first shop I took the MacBook to couldn't figure out the issue at all. Then I got recommended another chain of certified repair shops, and they figured out the battery issue. I guess the moral of that story is; don't give up - and try another shop if the first one can't fix it. 🙂

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