Id bet my last dollar its a heat issue somewhere. Monitor your temps while gaming. If it is a heat issue you almost have to force vsync on at 60 hz to cap your frame rate. Run away frames with vsync off might give you 100s of fps but it also generates a ton of heat. I would make sure your gpu fans are running 70% at min while playing this game and make sure your cpu temps are under 60..
I hate to say this but this game is poorly optimized and if your not careful it can kill your hardware.. Some of these new gpu cards have the fans set to such low threshholds and I think on purpose to burn out chips quicker which means you buying new stuff more often.. I don't trust amd or nvidia's fan software to do what is should so i use afterburner and manually set fans to always be on..

Back in 2005 I was in a beta for a game I can't recall but it was also poorly optimized and caused heat issues that burnt out my video card. The problem was I had no idea it was happening.. Then the next thing I knew there was graphic tearing across the screen in game, then on desktop.. The card was toast..

Point is, check your temps.. I saw some people on steam complaining about massive heat issues and crashing..

i did testing, its not overheat - i even set the cooler to kick up when to hot, and experimented a bit with radeon software...
then it was fine for some patches and months
and now its back, tempertature still moderate

i monitored it again and i think you are right - even with settings only on "high" not "very high" its very hard to keep the GPU under 70°C
altough my fan runs with 2.700 RPM, its crazy! thanks for your tip!

€: however, it was fine for some patches and months!