(In reply to Alex Deucher from comment #1)
> Does booting with:
> radeon.runpm=0
> on the kernel command line in grub help?

Nope. Same behavior. A couple of seconds i can see things running but then
everything becomes very slow and in another second whole system freezes. Funny
thing that mouse cursor still works (freezes from time to time but movable),
but can't switch to plain terminal by Ctrl+Alt+FX anymore or to do any other
action. Another thing that fan starts running with crazy speed, so it means
that in the background something happens and makes videocard/processor rather
loaded.