Best way to undervolt?

Lockheed · 2011-05-11 08:16:33

What is the best way to undervolt C2D on Arch linux? I am coming from Turion platform and there I used a program dedicated to AMD cpus.

demian · 2011-05-11 08:41:10

Try phc-k8 (http://www.linux-phc.org/)

Lockheed · 2011-05-11 08:45:19

phc-k8 is for AMD cpus.
I tried installeing phc-intel and phctool, but the later one is market as outdated in AUR and when I try to run it, I get

$ phctool
  File "./phctool.py", line 14
    print "pyGTK missed"
                       ^
SyntaxError: invalid syntax

even though I have pyGTK installed.

demian · 2011-05-11 10:00:57

Just phc-intel then. Install it, run /etc/rc.d/phc-intel setup. Then you should be able to modprobe it.
Control files are in /sys/devices/system/cpu/cpu*/cpufreq/.

P.S.: You might have to rmmod acpi-cpufreq. Also you probably want to add phc-intel to the DAEMONS=() and MODULES=() arrays in /etc/rc.conf and your voltage values in /etc/conf.d/phc-intel.

Last edited by demian (2011-05-11 10:05:10)

EiyuuZack · 2011-05-12 21:27:59

I undervolted my laptop without phctool using a mix of the Wiki ( just this step ) and then referred to this guide starting halfway on step 3 to check whether said phc_* files appeared, and then proceeded from there.

Two things to note:

- First, I used the script supplied there but with a few modifications ( as it is Debian oriented ) -- simply removed the aptitude parts and added a check for cpuburn. I'll post my version here if anyone wants it. I also killed X and ran the script from a tty to achieve minimum program interference.

- Second, on step 5 of the guide it is said to add the values you got from the script to rc.local to apply them at boot time. No need as there's a file in /etc/conf.d/ called phc-intel which is used by the phc-intel daemon to set the VIDs (Voltage IDs) values like demian said, so just add the values you obtained to that file and add the daemon to the DAEMONS list in rc.conf.

By the way, I don't remember if the guide mentions it but I should probably point out that if, or should I say, when your PC/laptop crashes while running the script you obviously need run it again after restarting to pick up from where it left.

Bear in mind that this script will strain your CPU causing the temperature to rise, the fans to go full force and the PC/laptop to crash, which can be scary I guess but in the end my CPU came out OK and nicely undervolted. Still, run it at your own risk.

Last edited by EiyuuZack (2011-05-13 00:43:57)

Lockheed · 2012-01-19 13:56:56

I tried doing what you wrote, EiyuuZack. However, I cannot compile this phc patch from step 3, because

test-release-0.3.199-3]$ make prepare
Makefile:25: *** Kernel build tree not found, maybe you need to install appropriate linux-kernel-headers for kernel 3.2.1-1-ARCH or run make with KERNELSRC parameter, e.g.: make KERNELSRC=/usr/src/linux.  Stop.

lagagnon · 2012-01-19 16:41:26

You also need to be aware that underclocking may not be stable and even though you can get the CPU to boot you probably should run "mprime" to ensure the CPU works as it should.

Lockheed · 2012-01-19 16:50:59

I know, I've been undervolting for the last 12 years on Windows.

Arch Linux

#1 2011-05-11 08:16:33

Best way to undervolt?

#2 2011-05-11 08:41:10

Re: Best way to undervolt?

#3 2011-05-11 08:45:19

Re: Best way to undervolt?

#4 2011-05-11 10:00:57

Re: Best way to undervolt?

#5 2011-05-12 21:27:59

Re: Best way to undervolt?

#6 2012-01-19 13:56:56

Re: Best way to undervolt?

#7 2012-01-19 16:41:26

Re: Best way to undervolt?

#8 2012-01-19 16:50:59

Re: Best way to undervolt?

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