I currently run a Cinema display which has reached the end of it's useful life and I've waited for Apple to launch a new display for too long and unwilling to pay a huge premium for a very old Thunderbolt display. I would like to use a Samsung 28"U28D590D which will only take a MiniDisplay Port to HDMI adaptor connection. The monitor has a resolution of 3840 x 2160 and Samsung say that it should display this resolution with this adaptor in my MacBook Pro Mid 2012 but everywhere I look I see users saying that it will not run at an acceptable refresh rate or that I need a specific version of the adaptor or that I need to use 3rd party software to increase the resolution. The Cinema Display runs at 60Hz and it looks like the Samsung will only run at 30Hz or perhaps only 24Hz. I do not intend to use this for anything other than general office work, architectural design using VectorWorks and Sketchup, Photoshop and Office and the occasional YouTube video but I'm not sure if 30Hz will be acceptable. I am happy to accept a lower resolution at a higher refresh rate or another monitor but clearly need at least 2560 x 1440 resolution which is the equivalent of the 27" iMac I also have. Can anyone advise please.