Hmmm..... If you've overclocked before without issues then it's probably the game's fault. Games that are in alpha or beta are usually not well optimized and will have issues to begin with but some times they don't play well with overclocked hardware. Try setting your clock speeds to default and see if the problem occurs. If not then set your overclock back to what it was and see if you have a problem then. if so, then it's the game not playing nice with your overclock. If the problem occurs when at default clocks then something else is afoot and will require more troubleshooting.