Hi all, I am wondering if anyone has some insight into this issue. I have two Samsung U28D590 (28" 4k monitors) I believe they are DP 1.2, but not certain. I have one each MSI Radeon 7970 and 7950, I have run both cards before doing the netkas EFI mod and they worked great in High Sierra over DP to produce 4k output. When I modify each card the display ports no longer work but I do get Mac boot screen over DVI and HDMI. The script runs with no errors and as far as I know they are successfully Mac EFI modded cards that might not be compatible with my monitors? The cards I purchased were cards that I have seen others online successfully mod. However no mention if they used DP or not. Why would modding to Mac EFI bios make the cards fail with my monitors, does anyone have insight on this so I can chase the correct problem? The bios mod was based on the rom on the cards and both cards work with my monitors over DP before modding. A while back, before going to a GTX980 I purchased a similar Radeon card from an ebay seller that states it was working with DP, but it did not work for me or my monitors for some reason. The seller probably did the same mod. Is anyone running a modded or genuine Mac 7950, 7970 or similar and using DP outputs supporting one or two 4k monitors? If so what card is it? What monitors are they? I'd like a decent card with dual 4k out without having to swap cards on a 5,1, and have Mojave native support. Maybe I already have it but need to change monitors? Why would the cards work pre-mod with my monitors over DP and not after? --- Post Merged, Oct 9, 2018 --- OK, so I just learned this from another thread thanks to LightBulbFun "its a known issue that the Radeon HD 79xx EFI will crash when booted with a DP1.2 monitor plugged in"