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LG UltraFine with DisplayPort?

H

HelloAgain16

macrumors member
Original poster
Nov 19, 2019
42
4
Hello alltogether,
I've got a little question concerning my new display. I would like to have an eGPU to power my LG UltraFine 5K Display and I always thought I need one of those RTX Founders Edition Cards with the USB-C Port to be able to drive it because the display only got a USB-C connector. But can I also use a DisplayPort to USB-C cable to drive the LG? Or is that another kind of signal that the UltraFine can't handle. Because if DisplayPort works, I wouldn't have to get the Founders Edition necessarily! Thanks for your answers!
 
As far as I know there were two versions of the
LG UltraFine 5K Display: the first could only be driven by a Thunderbolt 3 source, the second one would also accept a USB-C Alternate mode input but only up to 4K.

The USB-C connector on the
RTX Founders Edition Cards does not seem to offer Thunderbolt 3 but Virtualink which seems to be a variation of
Alternate mode, which means it would only work with v2 of the display and only up to 4K.​
​
​
 
Thanks for your reply! So I have the Version 2 of the LG Display and 4k@60 would be enough for my purpose! So the VirtualLink would work right? But what if I try it with DisplayPort? Has anyone got experience with that?
 
I use the 5k DisplayPort to type-c by moshi. Apple sells it on their site as well. I use it with an eGPU (rx580) and it outputs 5k on Mac and 4K in bootcamp (may work with default bootcamp video drivers but I use others). The downside is you can’t control the monitor brightness or volume with the DisplayPort cable like you could with a typical thunderbolt 3 cable. At least I have not found a way.
 
Thanks CrashOveride for your response! Just got one more question! Does the Thunderbolt solution give you a significant performance loss when using bootcamp?
 
Crash0veride said:
I use the 5k DisplayPort to type-c by moshi. Apple sells it on their site as well. I use it with an eGPU (rx580) and it outputs 5k on Mac and 4K in bootcamp (may work with default bootcamp video drivers but I use others). The downside is you can’t control the monitor brightness or volume with the DisplayPort cable like you could with a typical thunderbolt 3 cable. At least I have not found a way.
Click to expand...

Just a note: In this configuration the Mac is faking the 5k output. It's actually 4k, just with UI scaling. Not actual 5k.
 
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HelloAgain16 said:
Thanks CrashOveride for your response! Just got one more question! Does the Thunderbolt solution give you a significant performance loss when using bootcamp?
Click to expand...
I'm not sure where you're anticipating a performance loss. Yes there is a minor performance loss on the eGPU via thunderbolt. I don't think there's any performance loss through the DisplayPort to Usb-C cable in particular. I should have also noted that the Utrafine shows up as 4k in bootcamp with a direct thunderbolt connection as well. This is ver well may be due to the third party drivers, but they're necessary to use an eGPU with a laptop with a discrete GPU.

It's listed as the first 5k cable certified by VESA, but it also seems to imply that this only via usb-c to DisplayPort 1.3/1.4 on the amazon listing. Again, still lets me use full 5k resolution on my Mac (if I wanted, though I choose scaled 2560x1440) via rx580 in sonnet eGPU enclosure. It also shows up as a 5k monitor in system information.
 
You can only run the LG Ultrafine 5K(even the latest version) at true 5K resolution over Thunderbolt 3. The only eGPU's that currently support this are the two from Blackmagic. You cannot output true 5K from a Displayport on the graphics card to the TB3/USB-C port on the monitor.

Regarding the Moshi USB-C to DP cable, 5K only works one way from USB-C(output device) to DP(monitor) and only if the output device supports 5K output. But in the case of the LG monitor, the USB-C output still needs to be TB3 for real 5K.
 
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So I now got a Razer Core X with an RTX 2070 Super Founders Edition. The graphics card is connected to the LG monitor via USB-C and so far it all works fine. But for some reason I have a performance loss of about 20%! Is this normal? Has anyone got experience with this?
[automerge]1582910974[/automerge]
By the way in BootCamp I use a 4K60Hz resolution!
I primarily use the GPU for gaming at 4K!
 
Yes a 20% thunderbolt overhead loss vs an internal GPU is normal. You're basically using a PCIeX4 connection over thunderbolt vs a PCIeX16 on an internal board so there is also theoretically a plateau of performance. I hear after a certain point there the gains become more minimal from nicer cards. That's more just what I've heard, but performance loss over TB3 is a guarantee. See below for some of the OG tests with explanation on the eGPU forum (great resource).

egpu.io

eGPU Performance Loss - PCI Express vs. Thunderbolt

This is the question that many users wants to know: How much performance drop of my Video Card i will have if i put it in the eGPU with Thunderbolt 1,...
egpu.io egpu.io
 
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Thanks very much for your replies! I appreciate it! So I now got the eGPU and it works really well with BootCamp but the performance loss is quite strong. In 3dmark I get 8300 points instead of 10300! So it is a around a 20% loss!
 
Hi, anyone here managed to get TRUE 5k60hz using DISPLAYPORT (output from graphics card) to USBC on LG5k monitor?

Is it 100% confirmed that graphics will max out at 4k with this method?

I'm considering to get an LG5k monitor to use with my windows PC.

Thanks
 
Hello sprockett! So for me when going to Windows settings to set the resolution it goes up to 4K but I can't select any resolution higher than that! I'm using an RTX card connected via DisplayPort to USB-C. The cable itself would be able to support 5K60 as far as I know (it's the Moshi bidirectional cable) but I think that the monitor can't work with this signal as it needs a thunderbolt signal in order to work with 5K resolution! I sometime ago watched a Linus Tech Tips video about that topic maybe that can help you to understand more what the LG5K needs as a signal source for 5K!
I hope I could help you!
 
Crash0veride said:
I use the 5k DisplayPort to type-c by moshi. Apple sells it on their site as well. I use it with an eGPU (rx580) and it outputs 5k on Mac and 4K in bootcamp (may work with default bootcamp video drivers but I use others). The downside is you can’t control the monitor brightness or volume with the DisplayPort cable like you could with a typical thunderbolt 3 cable. At least I have not found a way.
Click to expand...
Hi, have you tried to use the LG with Displayport adapter with an older computer? Like at 2K...I was thinking I could juggle it between new mac mini and a 5,1 mac pro.
 
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