I have a Nvidia GeForce 770 graphics card with 4mb DDR5 onboard memory. I've been flying the DX11 version and getting screen freezes and CTDs with some frequency. The other night I flew the DX9 version without a problem. Out of curiosity, I just did a general web search for my card and DX11. Lots of gaming issues out there with, wait for it, freezes and CTDs for lots of games. This doesn't appear isolated to AH. Lots of advice on what to do, but the general theme seems to be, use DX9. Just an FYI.