Is there a way to disable specific CPU core?

[shreedx]

Hello, my iMac is crashing all the time and all the error reports point at CPU core #3. I would like to test disabling it. All the options I found only limit number of cores in use, but I haven't found an option to disable just a specific CPU core. Is there any way to do this? thanks!

 

[treekram]

This issue seems to be easily searchable so perhaps you have found a solution. I saw a couple:

https://forums.macrumors.com/threads/can-you-disable-cpu-cores-in-osx.1698844/

https://www.whatroute.net/cpusetter.html

In both cases, you can limit the CPU's used, not disable a specific CPU. If you don't already have Xcode, you might want to try the CPUsetter program since the Xcode download is over 5GB - but Xcode is from a trusted source - I haven't tried CPUsetter. Xcode now looks different that what is in the thread linked above but the functionality is still there. You can also try disabling hyperthreading to see if that makes a difference. You lose maybe 15-20% performance in situations where hyperthreading would have been invoked.

In terminal, type in the command:
sudo nvram SMT=0 (to re-enable, do sudo nvram -d SMT). The computer has to be re-booted for this to take effect.

In your kernel panic (or other) report, if there is a specific program that is consistently triggering the crash, it might be the program unless the program is one that is known to run multiple threads simultaneously, such as HandBrake.

You might also want to try running in safe mode.
https://support.apple.com/en-us/HT201262

 

[shreedx]

This issue seems to be easily searchable so perhaps you have found a solution. I saw a couple:

https://forums.macrumors.com/threads/can-you-disable-cpu-cores-in-osx.1698844/

https://www.whatroute.net/cpusetter.html

In both cases, you can limit the CPU's used, not disable a specific CPU. If you don't already have Xcode, you might want to try the CPUsetter program since the Xcode download is over 5GB - but Xcode is from a trusted source - I haven't tried CPUsetter. Xcode now looks different that what is in the thread linked above but the functionality is still there. You can also try disabling hyperthreading to see if that makes a difference. You lose maybe 15-20% performance in situations where hyperthreading would have been invoked.

In terminal, type in the command:
sudo nvram SMT=0 (to re-enable, do sudo nvram -d SMT). The computer has to be re-booted for this to take effect.

In your kernel panic (or other) report, if there is a specific program that is consistently triggering the crash, it might be the program unless the program is one that is known to run multiple threads simultaneously, such as HandBrake.

You might also want to try running in safe mode.
https://support.apple.com/en-us/HT201262

Thanks for your reply. Yes, I was able to limit the cores, but since I know core #3 is the problematic one, I would like to disable just that one specific core. For the moment, I had to limit my iMac to use only 2 cores (#1 and #2) but I haven't found a way to disable just the one specific core.

I did it through terminal, using: sudo nvram boot-args="cpus=2"

Unfortunately both Xcode and CPUsettler only provide ways to limit cpu core usage, not specify which one not to use :/.

I did a clean install of Mac OS X and it kept crashing anyways, sometimes even during boot, so I think there is some sort of a HW failure, not a SW one triggering the reboots.