Mac Mini 2018, Razer Core X, RX 5700 XT, & 3 monitors
Clear all

Mac Mini 2018, Razer Core X, RX 5700 XT, & 3 monitors  


New Member
Joined: 6 days ago

I can't keep 3 4K UHD monitors successfully connected and active on my Mac Mini regardless of what combination of eGPU/iGPU connections I'm using.

Mac Mini 2018

  • 3.2GHz 6-Core Intel Core i7
  • 64GB 2667 MHz DDR4 RAM
  • Intel UHD Graphics 640 1536 MB
  • Mac OS Big Sur 11.1

Early November Added (Using Mac OS X Catalina):

3 4K UHD monitors:

  • 1x - LG 27UD68-P
  • 2x - LG 24UD48-B

Mac Mini technically supports the 3 monitors on the iGPU. Had them connected via HDMI (27 inch) and Thunderbolt 3 to Display port for the 24 inch monitors (1 connected to each Thunderbolt bus). Issue was that when the Mini would wake from sleep, the HDMI monitor would not wake up. Started having this issue using last update of Mac OS X Catalina prior to release of Big Sur. Worked fine for 6 months before that.

Initial installation of eGPU was rocky. Ended up using the SwitchResX and Hammerspoon solution I found here:

Only difference was my setup was all 3 monitors connected to eGPU using Display Port connections. I did not keep a monitor input directly connected to the Mac Mini as outline in the solution above.

Things were working great until last week when my monitors started shutting off while I was actively using the computer. Not one monitor, all three at the same time. Was occasionally able to connect the 27 directly to the Mini via HDMI and get an image to shut things down, but, more often than not, ended up doing a hard shutdown and reboot. Would turn off the eGPU and turn it back on as part of this process. This is obviously not a productive use of my time during the work day. Especially since it started happening frequently. Researched the forums here and started to wonder if the upgrade to Big Sur or applying the last update might be part of the issue, since I don’t think I disconnected the eGPU while updating. 

I did a clean reinstall of Mac OS Big Sur, using the HDMI connection with a single monitor, and reinstalled all the software I use regularly before I reconnected the eGPU. Still having issues with the eGPU connected monitors shutting down randomly. If all 3 are connected to the eGPU it eventually causes a kernel crash and the computer reboots. 

I’m currently running with the 27 inch monitor connected via Thunderbolt, bus 0. While the 24 inch monitors are connected to the GPU. The eGPU connected monitors operate as expected for anywhere from 5 to 30 minutes and then just shut off. The system still seems them as active monitors though. They show up in system preferences and I can move windows over to them. To resolve the situation I have to close any active applications that were on those monitors, disconnect the eGPU, turn it off, turn it back on and then they will work again for 5 to 30 minutes. 

Just wondering is anyone else is experiencing anything similar under Big Sur with a similar setup. Hard to diagnose if this is just a Mac Mini issue (which I suspect may be true since I have issue with 3 monitors connected and no eGPU) or if both have unrelated issues. I wouldn’t have a problem keeping 1 monitor connected directly to the Mini if it meant the ones connected to the eGPU would work, but that doesn’t seem possible right now.


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