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I have a MacBook from a few years back. When I use it write some code and browse the internet, the fans go very fast and the noise is horrible. But the temp shows only 70 C.

So I used SMC to force the fans to 3000rpm. I really don't mind frying my MacBook as long as its quiet. Now instead of the temp rising to 90 C or more (what I want!), my MacBook decides to lower the cpu clock to 0.8 Ghz. And it becomes completely useless. I can't even use one program at a time. Even the mouse cursor lags.

What can I do? Can I force the CPU clock?

Model: A1286 i7 2.0 Ghz (High Sierra) Early 2011

edit: i don't even want a turbo boost or anything (would be nice). i just want to use the 2 Ghz and not only 0.8 Ghz.

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  • 3
    be specific which exact model? – Steve Chambers Apr 21 '19 at 0:36
  • I am a bit confused. As far as I know you cannot set maximum speeds for the fan, only minimum. I understand that there is thermal throttling going on. I don't think this can be overruled. There are tools to disable TurboBoost on certain Intel CPUs, which may help a bit to keep the Mac cool. – n1000 Apr 21 '19 at 10:25
  • @n1000 it is possible using the terminal interface: github.com/hholtmann/smcFanControl/tree/master/smc-command i think you miss-understood my question. i don't want to keep my mac cool. i want it to get really hot and use the full clock speed not just 0.8 ghz. – swisswiss Apr 21 '19 at 10:43
  • @SteveChambers i updated the question. – swisswiss Apr 21 '19 at 10:44
  • There are different temperature sensors. On the CPU, heatsinks, GPU, etc. If any of those hit their upper limit the Mac starts throttling as a last resort. This is what you are seeing. I think this is implemented low-level and I never heard of tools that would allow to override this. However, I also had not know that SMC can set a maximum fan speed :) Curious to see if there are any answers. Another reason that Macs throttle is when the battery is damaged and cannot buffer peak loads anymore. Is your battery ok? – n1000 Apr 21 '19 at 10:49
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That sounds most probably like an old Mac, which will not go very fast anyway these days.

But the symptoms really can describe a few things of underlying problems.

  • misconfiguration: look at the programs installed and delete what's unneeded, especially background applications (make a clean install ot the OS if all else fails)

  • SMC settings got confused: perform an SMC-reset

  • aging hardware: the thermal grease could be bad by now and might need replacement (try the other options first)

  • being dirty: if the grills for the fans are clogged (most probable here) just open the case, clean it out.

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  • i might try a fresh install. that seems like the only plausible fix. hardware issues are most likely not the cause here, since the throttling happens at 70C and 70C seems like a software set max. – swisswiss Apr 21 '19 at 11:11
  • @swisswiss It wouldn't hurt to just look inside and examine the fans. HW that old will have dust inside and when the airflow (suboptimal in 2011 anyway) gets degraded then the sensor readings tell you not as much as you'd like. – LаngLаngС Apr 21 '19 at 11:22
  • i did open it just now and remove some dust. it didn't have much since i do that every year or so. still it seems to me the fans work quite well. they manage to bring down the temp from 90 to below 70 in a few seconds but they are extremely noisy. – swisswiss Apr 21 '19 at 11:36

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