Does anybody know how to disable OSX from throttling/underclocking the CPU on a Macbook when the battery gets low on power? I think the feature is called SpeedStep. The problem is that my battery is damaged and no longer works so I have to run my Macbook off of the power adaptor and I would like the system to run up to speed, instead of at 0.8 GHz, so I can use it until I get a new battery. I have a Macbook Pro 13" Late 2013 i5 2.6 GHz with Retina(11,1). It's running OSX Yosemite 10.10.2 with Darwin kernel version 14.1.0.

I've already tried these kernel patches with no luck: perl -pi -e 's|\xe2\x00\x00\x00\x02\x00\x00\x00|\x00\x00\x00\x00\x00\x00\x00\x00|g' kernel perl -pi -e 's|\xe2\x00\x00\x00\x4c\x00\x00\x00|\x00\x00\x00\x00\x00\x00\x00\x00|g' kernel perl -pi -e 's|\xe2\x00\x00\x00\x90\x01\x00\x00|\x00\x00\x00\x00\x00\x00\x00\x00|g' kernel I've also heard of a "NullCPUPowerManagement.kext" kernel extension, but I'm not sure if that would work on my system. I know there are some hackintosh boot loaders, such as clover, that support modified SSDT and DSDT, but I'm not sure if that will work for my problem. Any help is greatly appreciated!

  • Very good question, I may add that I will be happy with any extra power, be it 1.5 or 2.0 Ghz! I will add a bounty to see if this get traction! – joao Beno Jul 31 '15 at 1:59
  • Err - there is a reason why the CPU throttles on low battery: On many MacBooks the power supply is slightly under-dimensioned and will not provide enough power under extreme load (e.g. while gaming). So the battery serves as a buffer to shave off peak loads. Therefore I recommend not to try that. – n1000 Aug 6 '15 at 20:17
  • Currently my CPU is using around 6 to 8 W, so I'm pretty sure we could step it a little higher without crashing the processor... – joao Beno Aug 7 '15 at 1:51

So, after researching more and trying other methods, what can I say:

  • How to disable the SpeedStep when using MacBook Pro without a battery? and it's answer pointing to “Fixing” kernel_task CPU Problems in MacOS 10.7/10.8 will help you with problems where processes take a lot of percentage from the processing time. Doing the trick will turn your macbook useable, but the Ghz will stay at minimum.
  • The new kernel power management works only from Ivy Bridge forward, so Macs equiped with Sandy Bridge or older processors still using the old power management and therefore the kernel patch won't work.
  • Removing AppleIntelPowerManagement kexts won't help, and NullCPUPowerManagement won't help too… I still get the same 0.8Ghz.
  • Using apps like SMCFanControl will help with controlling the fans, so any reply that helps getting the original clock are welcome as the chance of burning the processor due to heat are diminished.

So for now I think that will be all. If I get any solution to work, I will report it here!

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You may have checked to see that this question has already been asked. So as not not add to the endless recursing of the internet, the answer to the question points here.

This is an older post and relates to OS X 7 and 8, though there are several comments with patches/updates for newer OS versions and hardware revisions (this started with Apple's move to Intel, so you should be all set on that front).

Note I do NOT recommend this. Macs are notorious for not responding to hardware modifications (yes, you are attempting a hardware modification), I suspect you will be delighted by the fact that your CPU now runs as 2.2 GHz for about 45 minutes until it overheats and shuts down. The increased temperatures (please measure and report back if you try this) will also considerably shorten the life of your MacBook as a whole.

As a P.S.: Intel's PowerGadget may allow you to view real-time scaling, so you can watch CPU activity (along with memory pressure, cache misses, and disk IO) as you run benchmarks and check your workflow, to see if the CPU is actually a bottleneck for you (I suspect it is not)

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  • Hello friend, as you pointed, this question was asked before, but the matter is that from OSX 10.8.5 onwards, power management is no longer done by kext, but instead built in on the kernel (As mentinoned here: insanelymac.com/forum/topic/…)... So, it doesn't matter deleting or moving the kexts mentioned on these links, power gadget will report the same 0.8Ghz, and the mac will still be super slow... – joao Beno Aug 3 '15 at 2:53

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