# CPU Underclocking doesn't work after reboot



## soulreaver1 (Nov 25, 2011)

Hi,

I'd like to permanently restrict the cpu frequency. I can do it by running 
	
	



```
sysctl dev.cpu.0.freq=995
```
 command as root. It works, and could be checked by command 
	
	



```
sysctl dev.cpu.0.freq
```
, it shows that cpu frequency is set to 995.
The problem is that I can't set it permanently (to work after reboot). I've ran following command (as root): 
	
	



```
echo sysctl dev.cpu.0.freq=995 >> /etc/sysctl.conf
```
 which should set it permanently, but after reboot command 
	
	



```
sysctl dev.cpu.0.freq
```
 shows maxiumum possible frequency, not the 995Mhz. Is there's something I've forgotten about?


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## phoenix (Nov 25, 2011)

You don't put the sysctl command into /etc/sysctl.conf.  Just the name of the sysctl to change, and the value to set it to.

Read the comments and examples in that file.  Or even the sysctl.conf(5) man page.


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## soulreaver1 (Nov 26, 2011)

Thanks, it's works like a charm! This article has made me wrong: http://www.elfnet.org/2010/01/12/underclocking-your-cpu-in-freebsd-8/ .Sorry


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