Well I've spent a few days setting up this new Dell 5k UP2715K. There were a couple well documented issues and I was able to get it working "fine" in Sierra 10.12.6 and Win 10 Pro. Beautiful 5K resolution @ 60 Hz, rich colors, super sharp text. I had everything working fine with only one last thing to check. Boot screens. I have NOT been able to get this display to show a boot screen no matter what I try. I have a Apple GT 120 in my cMP to use just for this case. I tried to get to a boot screen with the GT 120 and a mDP to DP (Dell) cable and no joy. I believe it's probably because the GT 120 uses DP 1.1 (?) and the display requires DP 1.2. So I popped in a flashed 680 (DP 1.2) and tried the same thing. No joy, black screen. Apparently this is an issue on both Macs and PCs as there is a lame FAQ from Dell that say's.... Well that's not much of a solution for me. I run one display and I'm not about to swap out displays anytime I want to see, or need a boot screen. This would be a deal breaker for me. If I can't get this display to show a boot screen I'll be returning it and stick with my 27" Cinema Display for now. So..... Question: Has anyone been able to get this display to show a boot screen? If so, what GPU, what is the trick ? Thanks !