Question How to get dual thunderbolt monitors working ?

[hipira]

Building a new PC and I'm having issues using dual LG UltraFine 5K thunderbolt monitors. I can only get one monitor working at a time. I'm using an ASUS Prime Z690-A montherboard, ThunderboltEX 4 expansion card, and Quadro RTX 4000 GPU.

The Nvidia control panel list both monitors but only one of them has the checkbox marked to use it. If I try to click the checkbox for the 2nd monitor, it does not check.

Because these are the older LG monitors, they only have one thunderbolt port so they can't be daisy chained. Each monitor is connected directly to the two thunderbolt ports on the card.

Any suggestions on what to try are greatly appreciated!

 

[Lutfij]

Out of curiosity, what BIOS version for the motherboard and driver version for Nvidia's control panel are you working with? OS? If you're on Windows 10, what version(not edition) are you on?

 

[hipira]

Out of curiosity, what BIOS version for the motherboard and driver version for Nvidia's control panel are you working with? OS? If you're on Windows 10, what version(not edition) are you on?

BIOS: 1003
Nvidia driver: 461.40
Windows: 10.0.19043

I've also found that if I connect one displayport from the video card and one from the CPU to the thunderbolt card then everything works. This makes me think it's some setting on the video card, but I haven't been able to find anything to fix it.

 

[phenry]

@hipira Could give a parts list and explain what you mean by connect 1 DP from the video card and 1 from the CPU (I assume you mean motherboard) to what? The mini DP in ports?

I also have 2x LG 5K monitors and want to setup a PC to do the same and I thought it just wasn't possible