3 Replies Latest reply on Sep 12, 2015 10:05 AM by allan_intel

    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).

      Screen Shot 2015-07-07 at 23.04.14.png

      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?

        • 1. Re: MacBook Pro (Early 2011) Underclocks CPU to 800 Mhz

          Hi AndreasSkielboe,


          Can you confirm that this processor is always behaving this way or just when idol? I would assume that if the board has been replaced and tested by more than one shop, then there is probably nothing wrong. Processors have power management states that can reduce the processor speed to low values, this is used with products like the Mac book* in order to save energy.

          • 2. Re: MacBook Pro (Early 2011) Underclocks CPU to 800 Mhz

            Hi hansb_intel,


            Thanks for your reply. I realize I should have been more specific.


            The CPU seems locked to 800 Mhz under any load I can throw at it. I have tried typical benchmark tools such as geekbench 3 as well as my own code and the frequency never rises above 800 Mhz. Geekbench scores are 1/3 of what they should be and the temperature never rises above 60 degree C.


            I understand that the processor has the ability to adjust its clock freuency in response to external factors such as temperature and available power and that some of that happens at the OS kernel level, some at the firmware level and some at the chipset level? I'm no expert in this so it's difficult fo rme to debug. Since the issue is the same on Windows and linux I exspect its not the OS.


            The issue begain in combination with changing the logic board and a broken battery. I know that underclocking is a thing typically related to broken batteries in MBPs, so I wonder if it somehow got stuck in the low frequency state even after changing the battery.

            • 3. Re: MacBook Pro (Early 2011) Underclocks CPU to 800 Mhz

              Apple has requested that all questions regarding Apple systems and software be addressed directly with Apple support. I recommend checking the link below for troubleshooting assistance on your Apple computer:

              MacBook - Apple Support