https://bugs.freedesktop.org/show_bug.cgi?id=46725

--- Comment #7 from Tomi Pieviläinen tomi.pievilainen+freedesktop@iki.fi 2012-03-12 03:15:07 PDT --- This has happened several times more to me. It happens very often when watching a HD video, and some times when viewing photos. Hasn't happened in normal desktop use.

I've also noticed that I can get it back on by forcing it off with xrandr, and then back on.