Power Saving Trick for Mac Pro

Posted by rae in hardware
at 12:04 am on Wednesday, 25 July 2007

I put this in my crontab:

# save energy by disabling unused CPUs
0 0 * * * /usr/bin/hwprefs cpu_disable 2; /usr/bin/hwprefs cpu_disable 3; /usr/bin/hwprefs cpu_disable 4
30 8 * * * /usr/bin/hwprefs cpu_enable 2; /usr/bin/hwprefs cpu_enable 3; /usr/bin/hwprefs cpu_enable 4

This turns three of my four CPUs off between midnight and 8:30am every day. Since each CPU burns a fair number of watts, I’m hoping this will save me some power costs. I looked for a way to set the CPUs to “power conserve” mode or something in the energy/sleep settings, but no luck.

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