My LG 5K arrived today. I'm using a mid 2015 MacBook Pro with the Radeon graphics option, fully loaded. Since 2009, I've only used my laptops, & made print decisions based on what I see on the 15" screens. What surprised me is that the Preferences screen indicates a full 5K resolution, contrary to the Apple support documents. So I went to the local Apple store & took screen shots of an 27" 5K iMac, & also a Mac mini & Mac Pro, both with the new LG displays (see attached pics). Notice that the mini correctly identifies the 5K display as running 3200x1800, but my MacBook Pro & the Mac Pro, both using a TB3-TB2 adapter indicate 5K. I pointed this out to the store guru, & his only reply was that the display must be wrong, because TB2 does not support 5K. So what am i seeing: 4K or 5K?