Since upgrading to Gutsy I could not notice that my computer was running hot and very hot all the time. But it was only when everything was so slow and hot that the Grub menu was appearing in slow motion that I decided to investigate the problem.
First probable cause: cleaning the fan
Unlike the I8600 the fan in the D820 is hard (see impossible) to reach. The official Dell guide shows you have to remove keyboard, hdd, display, CPU in order to reach the fan. HUH!! In the end I just used the vacuum cleaner to aspire the fan as much as possible.
Second probable cause: speed-stepping not working
Since cleaning did not shown any improvements I decided to check the speed-stepping on my Core 2 processor. I decided to follow several guides I found on the internet such as this one and remove powernowd. In short I did these steps:
apt-get remove powernowdmodprobe speedstep_centrinoFATAL: Error inserting speedstep_centrino (/lib/modules/2.6.22-14-generic/kernel/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.ko): Device or resource busy
This should have been the module of choice for my Core 2 DUO but it did not worked.
modprobe p4_clockmodormodprobe acpi_cpufreq
worked but after loading the p4_clockmod the
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
only showed a max speed of 1GHz.
I loaded the rest of the modules in /etc/modules and installed cpufreq-utils
cpufreq_conservativecpufreq_ondemandcpufreq_powersavecpufreq_statscpufreq_userspace
and the speed-stepping was working in the range 800MHz – 1GHz. Does not look good when you are having a 2GHz processor.
After some more reading I found this might be bios related so I upgraded the BIOS to A07. Fortunately I managed to upgrade easy enough but it did not fixed the problem.
In the end I removed the modules, disabled cpufreq-utils and reinstalled powernowd.
Third probable cause: something is eating my cpu
Since I was not running anything special except a web browser and a mail client I did not thought about this at first. I knew evolution was eating a lot of cpu for it’s spamassasin filter but doing a top showed something I missed before: firefox-bin. The firefox process was never getting bellow 50% at all time and it was lot of time at 80%. HMM, I should have some flash opened pages or bad plugins. I disabled most plugins and opened a simple which contains no flash. Still firefox was remaining at very high CPU levels all the time. I continued by disabling javascript with still no visible results.
The improbable cause: IPV6
After lot of reading the forums I found out some guys saying that ipv6 can hurt Firefox performance. So I added
blacklist ipv6
to /etc/modprobe.d/blacklist. After reboot this magically solved my problem. CPU usage dropped to under 10%. I could have banged my head twice yet still not finding such an improbable cause.