https://bugs.freedesktop.org/show_bug.cgi?id=65963

--- Comment #17 from Maciej gutigen@outlook.com --- Ok, it was fine during around 7 or 8 hours of usage (mostly browsing in Chrome, some gaming, a tv show with smplayer and vdpau). However today it started happening again.

To clarify, my system is (fresh installation made yesterday):

Ubuntu 14.04 64bit Kernel 3.16-RC7 from mainline repo Mesa git from Oibaf PPA HD7770 1GB

Switching to kernel 3.15.7 doesn't help.