Comment 5 for bug 1070531

Overheating when using the open-source radeon driver was a known problem (even on single GPU configurations) which has recently been addressed in Ubuntu 13.10 "Saucy Salamander". See https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/887842/comments/14 for further info but note that you don't need to fetch the updated firmware files if you are using Ubuntu 13.10 or later - they are included. Further to the information in that comment, the 3.13 kernel will also have support for dynamically powering down discrete GPUs on PowerXpress systems - see http://lists.freedesktop.org/archives/dri-devel/2013-November/048316.html and http://lists.freedesktop.org/archives/dri-devel/2013-September/045650.html for details.