Razer X Chroma eGPU w LG Ultrafine 4K Display + Macbook Pro 2018 troubleshooting
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Razer X Chroma eGPU w LG Ultrafine 4K Display + Macbook Pro 2018 troubleshooting  


Nick Pfosi
New Member
Joined: 3 weeks ago

Hi all,

~~ Quick aside: provided build details at the end \/ ~~ 

I am troubleshooting connecting my LG Ultrafine 4k Display directly to my Razer Core X Chroma with AMD's Radeon RX 5700 XT 8 GB graphics card. I use 2 external displays as well as my internal Macbook Display (HP, LG, internal, details below)

I connected my HP display directly to the RX 5700 XT via an HDMI cable - no problems. I also had no problems with macOS recognizing and utilizing the eGPU. I went through my main programs and set the "Prefer eGPU" setting but then discovered the set egpu script and ran that successfully. 

When I run the Heaven benchmark on Ultra on the HP display I get about 60FPS with peaks much higher than that - playback is smooth - I'm happy. 

When I run the Heaven benchmark on Ultra on the internal display OR the LG Ultrafine Display I get around 20-40 FPS and it stutters pretty consistently. My assumption is that this has to do with the TB3 connection between the LG display and the eGPU bottlenecking, so I'd prefer to run the LG display directly off the eGPU. 

The problem is, as others have reported on this forum, the issues with connecting the LG Ultrafine 4K (which is TB3 only) to the eGPU. I've tried a zillion dongles and cables from Micro Center and you can guess how that turned out (display didn't turn on with any of them).

1. I'm finding on the forums that the Moshi USB-C to DisplayPort Cable works for the first generation 4K displays (and the 5K Ultrafine) but not the second generation 4K Ultrafine? How do I determine which iteration of the 4K display I have? Apologies if this has been asked/answered but I've looked through the forums for days now and haven't found confirmation that the Moshi cable should work with the 4K display (only the 5K) or what the differentiating factor between these two versions of the display are (I know one supports DP alt mode but Idk how to determine if that's the one I have). I'm skeptical that the Moshi cable will work but maybe someone here has a similar use case? 

2. Second, and I know this is a stupid question but I can't find a reliable answer: Where is the best place to download the Windows version 1809 that is recommended when using Bootcamp and an eGPU? It seems like a given that one has access to that .iso file but I can only find "Upgrades" (msu files). 

3. Lastly, I generally use my internal Macbook Pro display while working (video editing) but would not be opposed to closing it if it improved performance... 
a) does clamshell improve or hinder performance? 
b) when I shut the laptop when booted into Windows the computer shuts down / crashes ... is this a known issue that the 1809 version might fix?
c) Would mirroring the internal display to a headless display plugged into the graphics card compel the graphics card to render the image on the internal display or is that naive? I bought 2 HDMI headless displays to test this for my Ultrafine and internal display and didn't notice an improvement so I'm assuming I've skipped some steps in my analysis here but wanted others' thoughts.


a/ Video editing
b/ gaming with Bootcamp (if I can get Bootcamp worked out)
c/ gaming with GeForce Now (streaming over a LAN connection 400-500Mbps up/down speed) on macOS

I only mention ~item c~ not because I necessarily think the eGPU is necessary or will help what I assume is a network-dominant task for my computer but because I notice that with the eGPU plugged in, if I am running GeForce Now on my LG display the performance is particularly bad - worse than no eGPU and certainly worse than when I play it on the HP display - so I'm wondering if that's because the display is visualizing the stream and bottlenecking on the TB3 connection? totally guessing but it bothers me so if anyone has some insight I'd appreciate it!


macOS Catalina Version 10.15.6 Macbook Pro (15-inch, 2018) 2.9 GHz 6-Core Intel Core i9 
Razer Core X Chroma
Akitio TB Dock (1 TB3 port with PD, 1 TB3 port w/o PD, 1 Displayport)



Radeon RX 5700 XT 8 GB graphics (3 DP, 1 HDMI)


Radeon Pro 560X 4 GB graphics
Intel UHD Graphics 630 1536 MB


23.5-inch LG Ultrafine Display (2x TB3 ports)
24-inch HP N246v Display (HDMI, DVI, VGA)
Internal Macbook Pro Display

Thank you all for your time and please let me know what more information I can provide to better help explain my situation.

My ideal outcome of course would be a 1-plug solution, presumably along the lines of:

HP Display > 5700 card > Razer X Chroma

LG Display > 5700 card > Razer X Chroma

Razer X Chroma via TB3 > (Akitio TB 3 Dock) > MBP via TB3 



To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.


Illustrious Member Admin
Joined: 4 years ago

@nick_pfosi, Your 2018 15-in MacBook Pro has four TB3 ports through 2 TB3 buses. Use them all if possible rather than daisy-chaining. The eGPU should always be directly connected to the TB3 port on its own bus for best performance.

I believe the 23.5-in LG 4K UltraFine is the 2nd gen and should work with USB-C monitor input. You can try the Moshi DP to USB-C cable. Get one from Best Buy online if the local Micro Center doesn't have it.

HP & LG monitor << RX 5700 XT eGPU <> left TB3 < MBP > right TB3 <> AKiTiO TB3 dock


external graphics card builds
best laptops for external GPU
eGPU enclosure buyer's guide

2018 Mac Mini [8th,4C,B] + RX Vega 56 Nano @ 32Gbps-TB3 (Gigabyte Gaming Box) + macOS 11 & Win10 2004 [build link]  

Nick Pfosi
New Member
Joined: 3 weeks ago

@itsage, thanks! I just ordered one. It'll arrive next week. I'll look for another bi-directional alternative that might come sooner but hopefully this will work. 

Where would you recommend I get Windows 1809? Is it possible to downgrade a recent download of Windows that I got from the Microsoft website? I've read about people doing that but am not sure how to do it (practically speaking). 

Also, what about clamshell? Or thoughts on why I notice a performance hit while streaming games over GeForce now? 


To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.


Nick Pfosi
New Member
Joined: 3 weeks ago

Hey all, sorry for the delayed follow up. Mixed bag with the update here. 

Good news: The Moshie cable arrived and worked - plug n play. Great. Wish I had tried it out sooner! There are a few lingering issues displays-wise though:

1) My HP display which is connected directly into the GPU via an HDMI cable often does not re-active / turn on when woken from sleep due to inactivity. Unplugging the HDMI cable doesn't re-activate the display either, only unplugging the eGPU does - which is a minor pain (i.e. ejecting and having all my programs reboot). After some observations and informal testing it seems that the likelihood of the display successfully waking up increases if I actually explicitly put the computer to sleep - something about when the displays disengage (not the screensaver which is always recoverable - makes sense, display never de-activated). Not a life-or-death issue but something I would be motivated to troubleshoot for sure. 

2) Lack of brightness control for LG Ultrafine monitor. I am assuming I also don't have volume controls but I never use the LG speakers but the brightness is a significant bother as for gaming / photo editing / video editing / browser I have different brightness settings I tend to prefer .. If I unplug it from the GPU and plug the display directly into my computer I can make an adjustment before reconfiguring the original arrangement with the eGPU and have the new brightness setting be 'locked-in' but this is also less than ideal... I've read on the forums about possible solutions but nothing that is directly applicable to my hardware or OS (that I've found). 

Beyond those two macOS based issues I've had significant troubles with enabling the eGPU on Windows Bootcamp. 

I followed the Bootcamp startup on the forums, looked into the Catalina hotfix and applied it correctly (I think anyway after poking around the post and testing it)... ran DDU, reinstalled the latest 2020 bootcampdrivers.com Adrenlin drivers... I disabled the FaceTime camera, the recommended PCIe bridges #1901 and the other details mentioned in the guide... I disabled as many devices as I could...  I tried multiple fresh installs of Windows 1903 but would always end up getting "yellow-banged" / Code 12'd. I am on Mac OS 10.15.7 which I was thinking might be part of the issue? I feel like I must have made a glaring and consistent error in my implementation of the steps but I find it. 

Thanks again for the recommendation of the Moshi cable though. I appreciate that. 


To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.


Noble Member
Joined: 3 years ago


There are many solutions for LG UltraFine 4K display:


For connection to eGPU, the Wacom Link Plus or Belkin Charge and Sync cable should work.

This post was modified 19 hours ago

Mac mini (2018), Mac Pro (Early 2008), MacBook Pro (Retina, 15-inch, Mid 2015), GA-Z170X-Gaming 7, Sapphire Pulse Radeon RX 580 8GB GDDR5, Sonnet Echo Express III-D, Trebleet Thunderbolt 3 to NVMe M.2 case

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