Abnormal behavior may occur using the UP2715k Dell UltraSharp with some Apple Mac platforms. Here are some of the issues you may encounter:
Issue: Apple MacPro MD770TA/A - displays a black screen when connected to a UP2715k display.
Solution: The MacPro MD770TA/A does not support DisplayPort 1.2 (DP1.2). Use a MacPro system that supports the DisplayPort 1.2 (DP1.2) standard.
Issue: When connected to a UP2715k display using a single DisplayPort connection (1xDP) system cannot show 4k2k resolution and when connected to monitor with Dual DisplayPort connections (2xDP) is detected as 2 separate monitors instead of showing 5k3k."
Workaround: The MacPRo ME253TA/A does not support Extended display identification data (EDID) with DisplayID tile display. If you connect a single DisplayPort (1xDP) connection to the monitor Mini-DisplayPort input (mDP) you can display 4k2k (max resolution).
Issue: If you connect a Apple MacPro a UP2715k display using the mDP input, the shows black screen.
Workaround: 1 To get 5k3k @ 60Hz - Update to Mac OS X Yosemite 10.10.3. Connect 2x mDP to DP cable to monitor.
Workaround: 2 To get 4k2k @ 60Hz - Update to Mac OS X Yosemite 10.10.3. Connect 1x mDP to DP cable to mDP port on monitor.
Issue: An iMac 27" Retina 5k Display with 10.10 connected using TB (Thunderbolt) to the monitor DP1 (blue label) shows only 2560x1440.
Workaround: 1 To get 5k3k @ 60Hz - Update to Mac OS X Yosemite 10.10.3. Connect 2x mDP to DP cable to monitor.
Workaround: 2 To get 4k2k @ 60Hz - Update to Mac OS X Yosemite 10.10.3. Connect 1x mDP to DP cable to mDP port on monitor.
Issue: No audio output from these systems when connecting to monitor DP.
Workaround: MacBook Pro 15" (2014, with Nvidia GT750M) can support 5k3k @ 60Hz with Mac OS 10.10.3. Older Macs do not support DisplayID. Connect 1xDP to monitor mDP for proper audio support.
Issue: UP2715K 5K display is only supported on Mac Pro (late 2013) with OS X Yosemite 10.10.3.
Workaround: Alternatively, if you don't have OS X Yosemite 10.10.3 support, switch to 4K resolution instead.
To display 4K resolution: