- Oct 20, 2018
- ASUS Prime Z370-A
- RX 580
The specs for the GC-AR state specifically "2 x Thunderbolt 3 ports supporting up to 40 Gbps bandwidth and a maximum display resolution of 4096x2304@60Hz" so I don't think the resolution is the issue. I tried connecting an HDMI display via a Aukey USB-C to HDMI adapter, and it works when it's the only device connected; I can use either one LG 4K display, or the one HDMI display via the Aukey adapter, but I can't use both simultaneously.The only thing I can think of that could be causing this problem is that the LG UltraFine 4K is slightly larger than a 4K display (3840x2160 or 4096x2160) at 4096x2304. Maybe the GC-ALPINE RIDGE has a bug in the firmware that does not allow two of them to be connected simultaneously even though they are connected to two different Thunderbolt 3 ports. That would be strange since Apple says you can connect four of them to an iMac Pro (but only at 8bpc).
Do you have a display that is 4K or smaller that can be connected to a USB-C port (with or without adapter)? Connect that display first, then the LG UltraFine 4K, then disconnect the first display and connect the second LG UltraFine 4K.
Anyway, I'm happy to report that today I received the GC-TITAN RIDGE card and am currently looking at two pristine LG 4K displays! The GC-TR, in addition to the TB3 motherboard cable, has another USB 2 header cable that connects to the motherboard, as well as 2 x 6-pin GPU power adapters to supply the stated 100W power delivery (no idea what you'd use this for? connect a laptop to your desktop to charge it?). I did connect the extra USB header cable, but I did not connect the GPU power connectors to the PSU, and the two LG 4K displays work properly. Brightness control, as well as sound output, works on both.