Black Screen Startup Issues Mac Mini
Give Apple feedback, this is a widespread issue. Workarounds are nice but Apple needs to fix this.
Can’t believe this issue is still around - wtf is Apple doing. Wish I had a mini + time on hand to debug.
I just sent Apple feedback, explaining that the Mac mini doesn't boot and that I have a workaround for it. I briefly explained the workaround and stated that users should not have to use a workaround in order to use their computers. They should fix it.
My mac mini does auto login for my user account (I am the only user). Without the workaround, it gets stuck on boot most of the time if only eGPU monitors are present. ie: It is not stuck at a login prompt. It just doesn't finish the boot process, it is just a black screen with no beep from BIOS. If users have been having this issue for multiple MacOS releases however, I somehow don't think it is a high priority. At least, I would bet that it's a security thing not to enable the thunderbolt ports until a certain point in the boot routine. But the boot routine doesn't get to the point where the ports are enabled because it hangs when it cannot reach the monitors.
This really only affects Mac mini users. And it is especially difficult if the mac mini and eGPU are not in a location where the rear ports are easily accessible (user needs to disconnect/reconnect for every restart). But. at least the workaround I posted above solves this issue for users who just want something that doesn't need to be touched. It can be used until Apple decides to fix the underlying issue.
@itsage Please add a warning to the eGPU Boot Camp Setup Guide on the main page: it still recommends the Mini in glowing terms, but new users are likely to hit a brick wall with the black screen and not be able to proceed.
@sdedalus1, It's hard to make a one sentence statement on something as convoluted as eGPU Boot Camp setting for any particular Mac. I'm far from an Apple apologist. I am a big fan of headless Macs and would like Apple continuing making them, especially the affordable ones. There is no other computer with a capable CPU, iGPU-only, and two CPU-connected Thunderbolt 3 controllers. It's not perfect but Apple has made firmware changes to provide Boot Screen support to the eGPU. The challenge is that there are too many different graphics cards to QA. Let's not forget Apple rarely ever support third-party hardware upgrades in the same way eGPU users have enjoyed.
I haven't had much time to test it, but did install 10.15.5 beta 4 today. I made sure I only had eGPU monitors connected and did a reboot to test. It worked perfectly. So it looks like next GA release will fix for everyone, as long as Apple doesn't break it again.
@davesignal, according to Sonnet Apple has addressed the issue in a bug report and is working on a fix now. You may be right that the next update may fix the problem. Fingers crossed.
I may have spoken too soon. I did do a 2nd restart since the first time and this time it didn't work without any workarounds.
EDIT: Nevermind. I think the issue I stated above may have been due to a different accessory I was trying to configure. I have since done 3 or 4 restarts since I made the above comment. And all have worked perfectly. So 10.15.5 may in fact be working. It is far more reliable than 10.15.4