I have a brand new iMac 27" retina 2017 to which I'd love to connect my UP2715K UHD 5K, but in 4k mode.
So I bought Apple Thunderbolt 3 to T2 adaper, connected it to T3 port on iMac and then I took a mDP-mDP cable supplied with monitor and connected it all together. And no luck.
Monitor goes to Eco mode because of no signal.
Please, pretty please, what I'm doing wrong? Is there any way how can I connect UP2715K to iMac Retina 2017, which has only Thunderbolt 3, but with original adapter to T2?
I don't need 5k actually, but if it would be working, like two DP ports on monitor connected with two Thunderbolt3 ports on iMac, I'll go and buy another adaper and try it.
Even with the usage of a TB3 to TB2 adapter, other Apple users have stated that our cabling is not going to work. You need to ask the Apple users what cabling and/or converters they purchased to get the UP2715K working on the iMac.
Just had the same problem with the same 5K iMac 27'' and UP2715K. Bought a Cable Matters Thunderbolt 3 to Dual 4K or Single 5K DisplayPort Adapter for Mac. Totally worked at full 5K on the dell.
"Note that although it uses a Mini DisplayPort connector, the Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter doesn't support connections to Mini DisplayPort displays."
As woolcap notes, you need a T3 to DP adapter (CableMatters, Startech, etc.).