I'm still under mojave and with the latest security/safari software update (Dec2019), I'm now unable to start my mac mini 2018 with the Radeon VII eGPU connected to an external monitor (through HDMI). To start my mac mini I have to connect it directly to the external monitor and not through the eGPU! Apple we need a software updt fix for this: very frustrating indeed!!!
The Mojave 10.14.6 Security Update 2019-002 contains the same bad firmware update that is also in Catalina 10.15.2 and wrecks (some) eGPUs. So if you want to keep your working eGPU, don't install that Mojave update either (I did, and you can't revert).
Workarounds: in MacOS, boot with eGPU disconnected and monitor connected directly via HDMI. At desktop, hot plug eGPU.
In Windows: install rEFInd and the modified apple_set_os discussed at egpu.io. This will allow you to boot into Windows and plug eGPU, but you will still need to disable resources in Device Manager to get around error 12. Another user reported using a USB-C to HDMI converter to boot with display connected directly to Mini, then hot plugging eGPU at Windows desktop, but I haven't tested that approach.
The Mojave 10.14.6 Security Update 2019-002 contains the same bad firmware update that is also in Catalina 10.15.2 and wrecks (some) eGPUs. So if you want to keep your working eGPU, don't install that Mojave update either (I did, and you can't revert).
Workarounds: in MacOS, boot with eGPU disconnected and monitor connected directly via HDMI. At desktop, hot plug eGPU.
In Windows: install rEFInd and the modified apple_set_os discussed at egpu.io. This will allow you to boot into Windows and plug eGPU, but you will still need to disable resources in Device Manager to get around error 12. Another user reported using a USB-C to HDMI converter to boot with display connected directly to Mini, then hot plugging eGPU at Windows desktop, but I haven't tested that approach.
This happened to me updating to 10.15.2. What I did was connect the monitor to the HDMI port on the Mac mini (As you stated), then reset the PRAM and NVRAM. You should boot up normally. When it restarts, unplug the Monitor and plug it back into the EGPU. It should recognize. And then reboot. It worked for me. Good luck.
I have the Razer Core X enclosure paired with a Sapphire RX Vega 64. This system was purchased at the same time the MacMini was released in 2018. It has been rock solid until the Mojave Security update -001 back in early Fall. With that update, the Apple Logo would always look squashed at startup (a few strange color bars would appear on the top part of the screen) and it would not correctly detect my screen resolution until after it arrived at the log-in screen. After I hit the log-in screen, it was flawless. I have been waiting for an update to fix this strange startup Apple logo color bar issue... but instead got an update that completely broke it!
I can switch back to the egpu once the computer has booted... but it will not boot if only my monitor (that has worked from late 2018 until this last update) is connected to the egpu. I don't have a second monitor to try a two monitor setup, but a single one for sure no longer works! Bummer!!!!
@ homedfrog, They've just issued out a new security update with no eGPU support fix however! I suggest that we all respond to the security update page feedback as not helpful and redirect them to this exchange!
Thanks Mac Carlos for the tip it worked the second time around!
I'd just add that in the first time I didn't have my egpu connected through the usb c port, so in order for this trick to work you'd have to have the macmini hdmi connected directly to the screen but the egpu needs to be connected to the mac mini through usb c! Great tip thanks allot!!!
I'd just add that this aint a permanent fix, my system is doing it again twice this week and each time I'm having to disconnect cables and reset the PRAM. It is definitely a software update that broke support of the eGPU, I can also confirm the bar artefacts showing up on startup back in october/november. Apple needs to come up with a fix soon. I've tried to contact Apple support to no avail! But if someone's (located in a world region that is accessible through apple support) can forward this discussion to them I'd be grateful! Thanks
I tried the "solved" answer but it did not work for my MacMini 2018 / Vega 64 egpu setup. If HDMI is used, it boots fine, and the egpu shows up for use once the machine boots. If a monitor is plugged into the egpu the computer WILL NOT BOOT, just stays stuck with a black screen and the fans (egpu and mini) all spinning at medium. I have to force the machine down before it will boot correctly with just the HDMI connected. I don't see an easy way to contact apple about this... and I wish the Pram / Vram reset would have worked for me but it was a bust.
Thanks for starting this thread and here is to a solution from Apple!!!
I have the same issue with the same hardware setup.
Mac Carlos' trick fixed the issue for me hope it does the same for you!
Good Luck!
Glad it worked
Thank you!
Thank you, I can report that this worked!
Sorry to hear that. What is your eGPU setup?
Thanks, I have the Sonnet eGPU 650 enclosure. This is has been on and off buggy since I updated to 10.14.5. Security updates should not break operation on supported hardware.
macmini egpu issue with dec 2019 mojave security/safari software update!
