I've just installed Ubuntu 14.04, I'm not sure if Radeon Dynamic Power Management is working because the laptop is hotter than my previous Ubuntu 12.04.4 with kernel 3.11 plus adding the kernel parameter "radeon.dpm=1" added in line GRUB_CMDLINE_LINUX_DEFAULT="quiet splash".
Please, could someone confirm that DPM is active out of the box in kernel 3.13?
sudo cat /sys/kernel/debug/dri/64/radeon_pm_info
. Source: askubuntu.com/questions/324733/… . Also the info about DPM might be in a different directory. Read the link for more details.