Oh, missed this thread. I built a new pc few months ago and started having exact same issue. Exact same build but I have the G1 970.
Commonly crash on round end or randomly during MGE. Not always an error message. Nfi how to fix, but it is now even more annoying because when I relaunch I don't get a rejoin prompt. Leaving casual/comp both greyed out and saying I'm assigned to a match. (y)
E: In the hope Jill or someone reads this thread, for a specific example, the other day I played two casual matches back to back on Hoodoo and both times as the bomb exploded on stage 3 I crashed.
E2: I use dx9. And same configuration on old pc with 8.1 had no issues. New pc crashes with or without one. I