The open source AMD Radeon driver got dynamic power management support with Linux Kernel 3.11. With this, the GPU and memory clocks adjust dynamically based on load, useful for saving power.
This feature is not enabled by default, at least in Ubuntu 13.10 (it will probably be enabled by default in Ubuntu 14.04) so here's how to enable it.
I don't have an AMD graphics card so I couldn't test this, but WebUpd8 reader towpik, who sent us this tip, says that using this feature, "the laptop is very cool and quiet. Finally!". Also, according to Phoronix, Radeon DPM is "fantastic for power use [and] thermal performance".
Please note that this will only work for Radeon HD 2000 graphics cards and newer.
Please note that this will only work for Radeon HD 2000 graphics cards and newer.
Enable AMD Radeon DPM (Dynamic Power Management)
1. To enable DPM in Ubuntu 13.10, you need to open /etc/default/grub with a text editor (as root) - I'll use Gedit below:
gksu gedit /etc/default/grub
And in this file, search for the following line (it's on line 11 on my system): GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
After "splash" add a space and then add this:radeon.dpm=1
After making the changes, this is how this line should look:GRUB_CMDLINE_LINUX_DEFAULT="quiet splash radeon.dpm=1"
2. Then save the file and run the following command to update the Grub:
sudo update-grub
3. And finally, reboot.
For Ubuntu 13.04 and older, you need a newer Kernel (since Linux Kernel 3.11 or newer is required) as well as an updated firmware. Since there are many things that can go wrong and I am not able to test this because I don't have an AMD graphics card, I won't post installation instructions for these here, but if you really want this, try these instructions.
Thanks to towpik for the tip, some info via Askubuntu