I bought one Samsung U28D590D to test 4k on the bigger and it's stunning. I have a Macbook Retina 15 mid-2012 that is now on 10.9.3, so I have the scaled options.On HDMI with the built-in port on the Macbook, like you guys it's stuck at 30hz, but with the separated screen option over picture in picture with a resolution of 1920x2160 @ 60Hz.I than bought Mini Display to HDMI, so I would end up with two HDMI side by side (dual HDMI), but realized that this crappy adapter is limited to 1080p. So read your posts and saw that it requires an active adapter Mini Display port 1.1 to HDMI 1.4a that will support the 1920x2160 @ 60Hz. So I have ordered one from Amazon (Accell B086B-003B-2) and should have it somewhere this week. Having two HDMI is probably the best option to correct the brightness issue with mini-display port to display port (monitor-in) mixed with HDMI to HDMI(monitor-in).My questions is : will Mac OS will be able to see it as one big screen when I got both "side by side 1920x2160 @ 60Hz"?Because Windows 8.1 can no problem, it detects a surround screen in the physx NVIDIA panel options. I saw that Apple released lots of Multi Stream/side by side compatibility with other monitors and more recent Macbook Pro Reinata 2013 and up. But there is NO WAY I am going to spend another 3000$ on a Macbook knowing that Apple can, if they want, release a driver that can do what we are trying to achieve. Macbook 2012 has lots of horsepower to drive Multi Stream HDMI at 1920x2160 60Hz to equal the 4K at 60hz.Any tweaks with that program swithcresX and if so any tutorial on the clocking and HIDPI? Because actually at 4k 30hz, the scaled is fantastic, just laggy mouse and laggy screen that moves. I don't want to play game with this, so I don't care about this limitation, I want to edit webpages, some pictures (even if not IPS, this monitor has freaking nice color matching by setting the monitor in "standing mode" in the angle). I was really surprised!Also, I was really surprised by Windows 8.1 scaled correction and nvidia support for 4k. I have Final Cut on MacOS, other then that I would consider buying premiere for Windows if Apple doesn't release a proper driver for my Macbook that is compatible with my Samsung side by side HDMIs.Anyways, thanks for your help and hope we can push Apple to release some good drivers so we all enjoy 4k @60hz without having to buy another Macbook.