I just bought a Philips BDM4065UC 4K 40" Monitor & am using it with my Mac Pro 3,1 with a GTX680 flashed with Mac EFI. The problem I have is that I can only use Display Port 1.2 & thus 60Hz refresh if I have another monitor connected too. If I only have the 4K screen connected I get no display even if I plug in a regular mentor to a DVI port after I have booted (HP LP2465 1920 x 1080). If I have both the Philips 4K & HP LP2465 connected then all is well except if I have the 40" 4K monitor I don't need another 24" monitor & it doesn't leave much space on my desk. If I set the monitor to Display Port 1.1 then I see the Apple boot screen & all is OK except I don't want a monitor with a 30Hz refresh as my main screen. I have tried switching between OS X driver & Nvidia web drivers without any change in behaviour. Is this a known problem or is there a workaround that I am missing?