Title says it all!
I'm thinking ThunderBolt 2 -> DisplayPort 1.2, into the LG. Supposedly the 10.12.1 update provided native 4K @ 60Hz output from Macs (like MacBooks 2015/2016) that were previously limited to 30Hz, a la the Late 2014 Mac mini.
The Iris 5100 integrated GPU should be able to handle 4K @ 60Hz, it's always been a problem getting it "out" of the Macs.
I'm thinking ThunderBolt 2 -> DisplayPort 1.2, into the LG. Supposedly the 10.12.1 update provided native 4K @ 60Hz output from Macs (like MacBooks 2015/2016) that were previously limited to 30Hz, a la the Late 2014 Mac mini.
The Iris 5100 integrated GPU should be able to handle 4K @ 60Hz, it's always been a problem getting it "out" of the Macs.