Ubuntu 11.10 and ATI radeon problem : fan always on

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Since I migrated my laptop (HP 4720s) to Ubuntu 11.10 with gnome-shell, I have the following issue :
  • the open source ATI drivers works well but my fan is always spinning
  • the additional drivers proposed by Ubuntu don't work and make gnome-shell unusable
  • the drivers (11.9) from AMD is very slow

So, for the moment, the best deal for me is to keep the open source drivers. DON'T INSTALL ANY OTHER DRIVER THAN THE ONCE INSTALLED BY DEFAULT. What we will do is to underclock the GPU to keep the temperature acceptable and avoid any problems with the fan. Let's open a terminal :
  • echo -e '#!/bin/sh\necho low > /sys/class/drm/card0/device/power_profile' | sudo tee /etc/init.d/ati-power-save
  • sudo chmod +x /etc/init.d/ati-power-save
  • sudo update-rc.d ati-power-save defaults 99
By the way, we will increase FPS by disabling vertical sync.

  • echo 'export vblank_mode=0' | sudo tee -a /etc/environment

Reboot and enjoy the silence!