Hi all,

I wrote a simple bash script to change the CPU usage according to its temperature.
I wrote this for my AMD Athlon 64 X2 (R) [2006] on Debian Wheezy (should also work on Ubuntu ...?). You'll need the packages lm-sensors and sed. Note that you have to start this as root or with sudo rights (to change the BOINC owned preferences file).

Suggestions and changes are welcome. I will update this post.

Use your favorite internet search enginge for your CPU's suggested temperature and set TARGTEMP.

#!/bin/bash
#Script to adapt BOINC's global CPU usage to CPU temperature
#Use your favorite internet search enginge
#for your CPU's suggested temperature
#Written for AMD Athlon 64 X2 (R) [2006]
#
#Released into the Public Domain or CC0, your choice.
#Thanks to grymoire.com, tldp.org, stackoverflow.com
#and all of the Open Source Community.

#Set target temperature of your CPU in Degree Celsius here:
TARGTEMP=50

#Set how often usage is changed and changes are put on screen in minutes
CHANGEPAUSE=1
OUTPUTPAUSE=15

#Simple check for dependencies
DEPENDENCIES="sensors sed"
for i in $DEPENDENCIES; do
if ! command -v "$i" >/dev/null
then echo "Please check if you have the package necessary for \033[1m$i\033[0m installed." && exit 1; fi; done

#Change to BOINC_DIR and create temporary folder for backup
BOINCDAT=$(grep BOINC_DIR /etc/default/boinc-client | grep -v "\#" | cut -d"\"" -f2)
cd $BOINCDAT
mkdir -p tmp

while [ -e "lockfile" ]; do
#Grab current CPU usage settings
CURRCPU=$(grep "<cpu_usage_limit>" global_prefs_override.xml | cut -d">" -f2 | cut -d"." -f1)
#Grab current temperature
CURRTEMP=$(sensors | grep "Core1 Temp" | head -1 | cut -d"+" -f2 | cut -d"." -f1)
#In-/Decrease usage by two percent
if [ "$CURRTEMP" -gt "$TARGTEMP" ]; then
ADVCPU=$(( $CURRCPU-2 )); else
ADVCPU=$(( $CURRCPU+2 )); fi

#Calculates pause for output on screen and also to log:
REMAINDER=$(( $(date +"%-M") % $OUTPUTPAUSE ))
if [ "$REMAINDER" = 0 ]; then
echo $(date +"%F %H:%M") Advised CPU is "$ADVCPU" %.\ | tee -a boinctemp.log
fi

#Stream EDit line with cpu_usage_limit by substituting CURRCPU with ADVCPU
sed '/cpu_usage_limit/ s/'$CURRCPU'/'$ADVCPU'/' <global_prefs_override.xml >tmp/global_prefs_override.xml
#Check temporary backup and copy to original (errors go to output AND into boinctemp.log)
if grep "<cpu_usage_limit>"$ADVCPU"" tmp/global_prefs_override.xml 2>&1>/dev/null | tee -a boinctemp.log; then
	cp tmp/global_prefs_override.xml global_prefs_override.xml
	else echo "Can't edit preferences file. Check your disk."
fi
boinccmd --read_global_prefs_override
#fi
sleep "$CHANGEPAUSE"m
done

Apologies to other flavour users but this should be easily adaptable.

---

My reasons to participate in grid computing:
1. I'm using true renewable energy (German accreditation; no certificate purchasing)
2. Production and disposal (will) amount to about 95% of the energy "used" during the lifetime of my PC
3. Helping