2018 Mac Mini - monitor problems

I’ve had my Mac Mini for almost 3 weeks now. When I first got it it had the same problem of not being able to wake up the monitor connected to the HDMI port (HP 32QHD Pavilion) and/or showing purple everywhere then static after a couple of seconds. It is important to say that I also had a USB 3.0 external hard drive case connected to one of the USB ports.

i decided to change the HDMI cable as a last resort before returning it. I also unplugged the external drive as i didn’t want to use it as my main machine anymore. Finally, I set the computer to wake up at 3am since I often go to bed and leave open documents to continue the following day. For several days the machine worked flawlessly, at least until I decide the plug in the external drive again, that once again brought the color problem with the screen going to static after a few seconds. I have tried to use it with and without the USB drive since and the machine still works flawlessly without the external drive plugged in, as soon as I connect it I go back to having monitor issues. I have a DAC connected via USB, it doesn’t seem to affect the monitor in any way.

In short...

• Fancy HDMI 4K certified cable from Best Buy solved the issue for me.
• Some USB peripherals seem to bring issues, some don’t.

I have a 2018 mac mini i7 which refused to connect to a single monitor over usb-c or hdmi on wake-up, re-start or boot-up. The machines been back to Apple for a new 'logic board'. This didn't fix the problem.

The good news is that following the advice below, which I read on this thread somewhere, seems to have fixed the problem / improved the situation:

• Go to Apple > About This Mac > Displays
• Click 'Displays Preferences...'
• Press 'option' key. This makes a 'Detect Displays' button appear bottom right of screen.
• Press 'Detect Displays' twice.

Thanks to the original author of this advice. Sorry, can't find the post again to thank you directly.

The other useful advice was: press option and command keys (not together) during wake-up/restart if screen appears dark.

I have a call booked with Apple tomorrow morning re this problem. I'll keep testing to see if this improvement is permanent or just temporary.

This started happening for me immediately after the supplemental 10.14.6 update in October 2019, and continued into Catalina. As I've had FileVault active since I got my 2018 Mac mini in December 2018, I'm not sure how I escaped this issue's effects for most of 2019. And, alas, that it showed up on a system update rather than at the time I enabled FileVault meant that it took me quite some time to discover it was FileVault related.

Anyway, confirming:

• It is FileVault related
• If my display is sleeping, I need to wake it before turning on my Mac mini, then I will reliably get the video signal

Just a heads up that I made at least one chat and two support calls and two Genius Bar appointments about this and nobody was cued to ask me "Do you have FileVault enabled? Oh yeah, you have to turn your display on before the computer" This resulted in my spending somewhere between 10 and 50 hours trying to track down the cause of the behavior as well as using up their support time trying to find out what was going on.

Given that it started happening with a software update, I'm guessing it is software-related.

I'm happy to be able to use my computer once again after a month or two of dealing with this, and happy that the solution is so simple. Given that a post in this thread says it's a known issue, it's frustrating that it's not part of the troubleshooting procedure for phone support.

At the same time, it's interesting that my startup procedures are so standardized, and I was so focused on trying to document the steps I was taking for the support line and Genius Bar appointments (I normally let my monitor go into power-saver mode rather than turning it off) that I never randomly discovered the workaround or connected that the occasional successful boot-up was actually the work-around in action and not that - my incorrect conclusion - it was an intermittent problem. *sigh*

The procedure that is working for me (Mac Mini + 27" LG, usb-c <---> usb-c cable):

• Boot: make sure the LG is awake before immediately turning on the Mini.
• Sleep: make sure the LG is awake, then press a non-printing key control, option, or command immediately.

If you are using a different monitor, your milage may vary... We may not have to be so fussy if 10.14.4 works as advertised.

Well, I saw this in the macOS 10.15.4 What's new.. "This update also includes bug fixes and other improvements:

• High Dynamic Range output to HDR10-compatible third-party displays and TVs connected with DisplayPort or HDMI

"

So I've updated, and guess what? No change. When connecting my 4K TV's HDMI cable directly to the the Mac mini's HDMI port, the boot up screen starts out in 4K, but then drops to 1920 x 1080 half way through the boot. If I log in, the system preferences -> displays still only lists 1920 x 1080 as the maximum resolution. HOWEVER, if I connect the TV's HDMI cable to a displayPort to HDMI adapter, the Mac mini boots in 3840 x 2160 and stays in this resolution. When logging in, preferences -> displays shows 3840 x 2160 as one of the options under the (*) Scaled windows.

NOTE: This is slightly different (and worse) from 10.15.3 in that the previous version of Cataline listed 3840 x 2160 as the "Default for display" but now, the default is 1920 x 1080 and I needed to switch to 3840 x 2160. Oh well, at least it stays in this mode through a reboot.

Steve

Nothing related to TB3-DP seem to have changed in 10.15.4 at all

While I found an adapter that seemed to work, its still busted functionality:

• Boot: Won't ever see the Apple logo - no input until logon screen on DP - HDMI works as it should
• Wake from sleep: Will sometimes crash the TB3-DP interface and nothing will get the screen to detect input on DP
• Switching inputs: Usually works - unless the iMac mini have been in sleep mode - otherwise crash TB3-DP interface

When the TB3-DP interface crash, not even unplugging and replugging the cable will work

Giving it the HDMI cable will give input

No FileVault at any time

I miss Steve Jobs and his focus on quality for price. Now its just for price and a logo.

When my brand new 2018 Mac mini goes to sleep and I try to wake it, the monitor does wake but there is no monitor picture. Yes, I've done all the suggested troubleshooting. No difference. I even tried screen sharing from another Mac mini and lo, the 2018 Mac mini thinks it has an INTERNAL IN-BUILT display when there is no picture on the monitor. See attached pic below:

In reality, it has a 19" 4:3 CMV LCD external monitor attached. I'm guessing this may be part of the problem.

After 10.14.5

Before 10.14.5

Let's hope that the firmware updates included in 10.14.5 to the Boot ROM and the T2 Bridge OS have now fixed the failure to wake from sleep monitor issue. Only time will tell...

Hi,

I have new mac mini 2018 and I started to have a display static problems after update to 10.14.5. Waking up from sleep is all OK. I have never expect any problems. But 100% cold start-ups from power off macmini, my monitor showing weird resolutions during apple boot logo. Later in login screen I see only static like an old TV without signal. In monitor menu I can read the current resolution which is 2021x1204@60Hz !? My LG monitor supporting native 1920x1200@60Hz. I have to unplug the DVI-HDMI cable from MacMini HDMI. All is OK until next power off. Restarting are OK also sleep and wake up. I tried to connect my 32" SONY TV via HDMI and there is no problem at all. The resolution 1080i is active from fresh start. It may be that the firmware of macmini have issue with some resolutions or cold handshaking with some monitors.

after unplug and plug back DVI-HDMI cabel

After I connect the new DVI - HDMI cable, tried to off night shift and also display detect as suggested in this forum, unfortunately nothing helped to solve my problem. However I figure out one work around to not disconnect and reconnect HDMI cable from Mac Mini every time from cold start. I used HDMI mini switch. This switch have one output and three inputs. It is enough to switch from port 1 to 2 and back. Basically it is the same as unplug / replug the cable. Hope that Apple will update the firmware soon and It will works as supposed to.

Is this identical to the problem I have. I have the Mac mini 2018 (2 days old) hooked up to a LG34WK95U. When I switch my Mini on, I see my monitor coming awake and then after a few seconds it says no signal and entering power saving mode.

When disconnecting the thunderbolt 3 cable and reconnecting again moist of the times I suddenly have a picture on my screen. Also forcing Mac mini off and then rebooting it sometimes restores the connection.

Is this the same known issue and under investigation?

Thanks, hope this will be fixed soon!

OMG, I thought I was going nuts! I have two Mac mini's and two LG 4k monitors and I'm having the exact same problem with both of them. This is beyond frustrating. I'm going to try turning off the file vault for now and see if that will work for me also for the time being. Thanks for posting!

I tried removing “File Vault”, but I have the same problem.

The problem arises sometimes when:

- I start the computer.

- I exit from stop (one or both my monitor black out).

I tried to resolve the root of the problem without success by:

- resetting the PRAM.

- trying all thunderbolt and HDMI's port in the back of the MacMini.

- changing various monitor's setting (resolution, calibration, ecc).

- changing various preferences in <Monitor> (<System Preference>).

- installing an app called SwitchResX but it didn't work.

Some temporary solution are:

- plugging out and in the monitor's cable.

- restarting one or both the monitors.

- shutdown and restart the MacMini (at least one monitor restarted).

- the command checking in/out the <Duplicate Monitor> in: System Preferences > Monitor > Disposition.

I found out that checking out all options in <Mission Control> (<System Preference>) has reduced frequency of the problem.

By the way my mac mini recognise my 2 monitors (LG 24UD58-B.AEU) as 27 inches in: Apple menu > About This Mac (it may be my fault?).

I hope Apple resolve his problem.

hardware:

Nome modello:       Mac mini

Identificatore modello:             Macmini8,1

monitors: 

2 LG Ultra HD:

Risoluzione:              3840 x 2160 (2160p 4K UHD - Ultra High Definition)

Aspetto interfaccia utente:       1920 x 1080 @ 60 Hz

Tipo di connessione:                DisplayPort

software di sistema:

Versione sistema:    macOS 10.14.2 (18C54)

I had a very similar issue. Plugging my 4K monitor into the HDMI output of the Mac Mini wouldn’t work (no display).I tried to connect it to the USB c using an HDMI adapter and that solved it.

When using the HDMI output of the Mac Mini display would work when using both the 4K screen and a second monitor plugged in. Apple support was no help.

I also noticed that the windowserver.plist files would not update when using the HDMI output. That also went away when I started using the USB c... Very frustrating and strange.

My only issue now is that the display wakes up on a delay, also strange and frustrating.....

I tried using a USB-C to HDMI adapter but had no luck. Maybe I should look at the windowserver.plist files?

I spoke with Apple. Their first troubleshooting step was reformat the hard drive and start over. I don't think that is reasonable. I might start with an external drive, though everyone here indicates the issue is definitely FileVault.