It has been addressed, many times before.

But I'm a nice guy, so instead of "lawl l2google nub" I'm going to reply like a non-sociopath:

Play with your flags. -v -w128 agression=11 works nicely for me, you might get better or worse with different values of w (must be powers of 2, w64, w128, w256 are valid, w100 is not)
Over/under clock your GPU. Get MSI Afterburner, bump core up to something like 975, bump memory down... as low as it'll go without crashing really.