LG Ultrafine 5k monitor...with PC!

[ohnoitsthomas]

Hey all! I am trying to get my LG Ultrafine monitor to work with a new build and having some trouble and looking for help! Using a Ryzen 5 3600, ASRock X570 Phantom Gaming ITX/TB3, Geforce GTX 1650 super....running Pop! OS.  

 

So I bought this ASRock mb simply because it had the ability to convert DP 1.4 into TB3 so I can use it with this monitor, but it doesn't seem to want to work! I have tested the build on both a standard HDMI display straight from the card and my wife's 4k LG with USB C in, which it works on, but it just won't seem to wake up the Ultrafine using the same config (dp in -> tb3 out). Any ideas? 

 

[jj9987]

My guess is Pop OS and Thunderbolt 3 configuration not being correct. What does bolt or tbt show (two most known CLI tools for TB3, does either detect the display)? Which authorization mode do you use?

[ohnoitsthomas]

12 minutes ago, jj9987 said:

My guess is Pop OS and Thunderbolt 3 configuration not being correct. What does bolt or tbt show (two most known CLI tools for TB3, does either detect the display)? Which authorization mode do you use?

Ok, so here is the trick, at my office (where the monitor in question is) I dont have another monitor available to trouble shoot this with. When I head back home I will take a look. 

 

So you think I probably just need to change my configuration with my OS?

[ohnoitsthomas]

34 minutes ago, jj9987 said:

My guess is Pop OS and Thunderbolt 3 configuration not being correct. What does bolt or tbt show (two most known CLI tools for TB3, does either detect the display)? Which authorization mode do you use?

Ok! So I forgot we had an old tv in the bathroom closet that I can use to check this with! I plugged in the the tv first then connected my LG display and everything popped on and the OS is recognizing it! I have no idea why this worked, but it did! A little concerned a reset is just going to bring me back to square one...anything I should check while I have it running?

[skittlebrau]

Posting this for the benefit of others who arrive here from searching.
 

I believe the reason OP couldn’t get this working is because the Ultrafine 5K requires two DP inputs on the Thunderbolt card to work because it’s a MST (multi stream transmission) monitor.
 

Pretty much all motherboards with Thunderbolt built-in have only a single DP input. You have to use a mATX or ATX motherboard with a Thunderbolt expansion card (motherboard needs a Thunderbolt header port too) since all the TB cards from Asus, Gigabyte and MSI have 2x DP inputs. Only those types will work with a LG Ultrafine 5K monitor, unless LG updates the monitor to support SST.