this is something I have noticed over the last 4 months. This is true for all the distros I have tested - ubuntu, debian, OpenSuse and Fedora.

After Gnome went to version 3, my system (Core i3 first gen, 4 GB ram, ATI HD5650) runs very hot.

When I say very hot, i mean it gets so hot that it turns itself off.

When I use fglrx driver for my ATI card, it's better, but I can feel the heat on my palms.

Using radeon drivers, on moderate usage such as browsing, the temperature ranges between 72 and 80 degrees celcius.

Using fglrx, it is in the early 70s.

If I start watching youtube videos, and the system is using radeon drivers, it will hit the 88 degree threshold and force a shutdown.

If it's on fglrx, it will hit the 80-84 degree range.

This problem is there only when I use Gnome 3 shell. When I use KDE, it runs at about 65-66 degrees on normal usage and slightly more when I am watching video etc..

I am in India and the room temperature is in the early 30s these days.

Unity is also decent, though not quite as cool as KDE.

I know that fglrx has been installed properly etc.. I get about 1200 frames per second on fgl_glxgears (without maximizing the window.) The highest I've ever got is 1800 fps under Centos 6.

My hunch, after testing on fedora, suse etc, is that this is an issue with Gnome Shell or GTK 3 in general.

There is also another 'bug'. When I got to Unity's system description, it says I am on a Vesa driver. Could this be the issue?

PS:when Gnome moved from 3.2 to 3.4, this improved slightly (about 30%). The experience is for gnome 3.4 on precise and f17.