Hi.. if your are using AMD Radeon Graphics in your system you need to turn on AMD Radeon DPM .it is not enabled by default in ubuntu 13.10 .Also note you need to have latest AMD Driver in your ubuntu .
You need to have root privileges for performing this operation
gksu gedit /etc/default/grub
search for the line
and add the folloeing to the line
whole line should look like this
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash radeon.dpm=1"
you need to update the grub by following command
Reboot the system to take effect
i got reduction in temperature after adding this.Hope you enjoy