Full 4K Resolution at 60 Hz
By default the Dell UP2414Q runs at 30 Hz for 4K resolution. But it is possible to not only run it at full 3840 X 2160 screen resolution, but also to run it at 60 Hz on the late 2013 MacBook Pro.
To enable 60 Hz operation, use the on-screen controls to enableas shown
Once configured as above, the UP2414Q supports 3840 X 2160 at either 30 Hz or 60 Hz.
The image below shows the display running at full 3840 X 2160 at 60 Hz (which looks the same as 30 Hz). Toggle the image to compare “best for display” mode, which in terms of text display acts like a 1920 X 1080 display (half-res), but with full display resolution for images and interface elements.
Refresh rate and resolution display can be erroneous
The Apple system information appears to be erroneous for resolution display at 30 Hz: the UP2414Q is absolutely delivering 3840 X 2160 resolution as shown below, yet it is listed as 1920 X 1080, in conflict with other information elsewhere (“About this Mac”). As shown below it is running at 30 Hz and is noted as “Television: Yes”.