macrumors 65816
Original poster
Aug 25, 2004
Pasadena, California, USA
I have been going nuts -- I have the following setup:

  • MacBook Pro 2019 16" with Core i9 and Radeon RX 5500M 4GB dGPU
  • Razer Core X w/stock TB3 cable
  • Nvidia GTX Titan Black 6GB GPU
  1. When I use Purge-Wrangler and reboot; the system freezes on the Apple Logo. The system fans then spin up fast and the machine shuts down.
  2. If I boot without the eGPU plugged in, then plug in at login screen, the eGPU is detected and it "pretends" the login screen is being output to the monitor, but it is only a black display on the external monitor (using HDMI AND DisplayPort)
  3. If I boot, login, plug in eGPU, the system freezes, then reboots about 50% of the time. The other 50% of the time, its fine. I then Go to "About this Mac" and see the Nvidia GTX Titan Black is listed as a GPU, but am unable to use it to output to another display.
I have tried the command pmset -a gpuswitch 0 command, which seems to be input correctly... but nothing happens. I'm at a loss.

I’ve tried the forums, but I’m still at loss as they reference troubleshooting guides I have already tried for the most part.

Anyone here have any ideas, since this is the natively supported architecture?


macrumors 68020
Sep 15, 2015
Portland, Ore.
Why are you messing with an eGPU? The 5500M is a pretty good GPU. The Titan Black is only like 30% faster, and reduced farther as an eGPU. I wouldn't personally use an Nvidia eGPU with a Mac that has an AMD GPU. It would be less headaches with a Mac that has Intel or Nvidia graphics. Also, from what I've read Catalina doesn't play as nice with eGPUs. Maybe you'd have better luck with a Mac that can run Mojave.

I found this thread that might be useful:


macrumors 65816
Original poster
Aug 25, 2004
Pasadena, California, USA
I bought an RX 5700 XT which works great under macOS but terrible under Windows. (Could not even get it to be recognized...) For some reason I thought that the 700-series GPUs worked great under both OS's so got this GPU.

Now, the nVidia card works great under Windows but does not work under macOS when using an external monitor. However, it still works for internal rendering, etc.


macrumors newbie
Jan 14, 2010
As far as I'm aware the only nVidia cards that work in 10.15 are older cards. The web drivers stopped working after High Sierra.


macrumors 65816
Sep 3, 2006
NVIDIA external gpu have never been officially supported in macOS. Apple put zero work on it.


macrumors member
Sep 24, 2017
Helmstedt / Germany
running into a similar issue:

MacPro6,1 with Razer CoreX TB3->TB2...i tried several gpu's now ( gtx770, gtx780, titan black ) and the only card what runs fine was the gtx780.
any of the other cards result in reboot loops. i hooked the razer to an MBA6,2 and its just fine there. also when i plug the cards in any of my other cMPs ( 3,1 and 4,1/5,1 ).

while the mp6,1 is running the latest mojave, all the other mac's run the latest big sur ( OpenCore helped me here ).

as soon as i plug in an AMD card ( rx580, hd7970, hd7950 ) the egpu runs just fine when plugged into the 6,1...
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