In the last few weeks I have been getting more and more requests along the lines of "will card XXX run a 4K display?" I have had to answer "I have no idea" Well, The Great Pumpkin brought me a Asus PQ321. So, we are going to figure it all out. To whit: I am starting with my favorite card of our creation, the EFI'd GTX570 2.5. These took a great deal of work to solve, and I am quite certain that every single one of these is "based" on our EFI work. Thanks of course to Nvidia for the drivers and original EFI. Anyhow, this is first card I will test with 4K. The good news...4K on DisplayPort !!! The bad news...Seems that boot screen isn't drawn in a way that translates to 4K, but I will need to experiment more. I waited a while and it just stayed grey. Good news is I might be able to fix that. The other bad news is that there isn't enough oomph to make this more than a desktop/web browser card at this res. I ran Valley at Ultra but backed off the AA...still a slide show. I may need to come up with a less painful benchmark. Anyhow, we will be testing ALL of our cards for 4K compliance in 10.9. We will update our listings as we get to them, but I will also be happy to answer questions from the curious.