Created attachment 119002 [details]
dmesg part 1 (png file)

Reproduced with Left 4 Dead 2, Distance and Metro 2033 Redux.

First the screen either freezes (Distance) or shows garbage, looks like many
small brown rectangles on the screen (Left 4 Dead 2, Metro 2033 Redux), then,
after around 30 seconds, the whole system freezes (keyboard/mouse doesn't
react, ssh connections drop, finally watchdog kicks in and reboots the system).

In between the 30 seconds I was able to grab some data via ssh. Screenshots
attached.

This is on a HD 6950.