Have a low end iMac, iMac 5K and a Mac Pro cylinder at work. Same but at normal iMac resolution (2880 x 1800) it plays at 70fps. I do NOT recommend the cheaper 4K TN panel displays like the Samsung U28D590D and ASUS PB287Q for anything but gaming. I know its a random game, but Batman Arkham Asylum as a benchmark mode - on everything high at 5K it plays at 25fps. We have it working at 5120x2880 with a 2010 Mac Pro tower sporting a GeForce GTX 980, the latest web driver, and some special boot-args in nvram.
Typically this is done on the network end, and if they spot any issues, like flash frames or audio hits or access luma (image is too white, IRE above 100) or temp footageany number of thingsthen those issues are flagged and they provide us with a report of things.
EDITREADY BENCHMARK IMAC 5K TV
MaUPDATE on the Dell 5K display (UP2715K). Whenever a show is delivered to a TV network, it is run through a process called QC, or Quality Control. Remember when we paid $3495 for the 23" Cinema Display (1920x1200) in 2002? Eek! And now you can buy a new Thunderbolt Display (2560x1440) for $999 (which also can act as a second display on the iMac 5K). The price has dropped from $3499 when that model was announced in July 2013 to the current price of $1499 MSRP. I recommend a quality 4K display with IGZO panel like the ASUS PQ321Q. However, if there is GPU intensive activity on both screens, the performance will drop approximately in half. If you have a static image (like Photoshop menus) on one display and GPU intensive activity on the other display, there will be no performance hit. Just keep in mind that one GPU is processing activity on both displays. You can definitely run a 4K Display at 60Hz on the new iMac with 5K Retina Display.
If we ran one copy at a time, the average was 1395 KSamples/sec. Next we ran two copies of LuxMark simultaneously rendering the Sala scene, one on each screen. If we ran one copy at a time, the average was 48 FPS. We ran two copies of FurMark simultaneously at 3840x1080, one on each screen. What will happen to display performance when there is a GPU intensive app active on both screens? But if you hold the Option key down and click the word "Scaled," it allows you to choose the maximum 5120x2880. The iMac 5K's System Preferences > Displays tile lets you scale the built-in display up to 3200x1800. After restarting the iMac 5K, we now had two displays running at 60Hz. We connected the DisplayPort of the ASUS 4K display to a Thunderbolt port of the iMac 5K using a DisplayPort-to-mini DisplayPort cable. PowerMax gave us access to a high quality IGZO 4K display, the ASUS PQ321Q 31.5".
EDITREADY BENCHMARK IMAC 5K FULL
The iMac with Retina 5K Display specifications page states it "simultaneously supports full native resolution on the built-in display and up to 3840 by 2160 pixels on an external display." We decided to see how well it handled a 4K external display. Updated on March 6th, 2015, with news on the Dell 5K display running at 5K on a Mac Pro. Posted November 21st, 2014 by rob-ART morgan, mad scientist