2018 Mac Mini - monitor problems

I'm having similar problems too. This weekend things took another strange turn though.

Config two monitors, 1 x BENQ (primary) connected via HDMI, 1 x LG connected via thunderbolt to DP.

Initially problem was second monitor, again LG connected via Thunderbolt to DP (Amazon cable), monitor would not wake and the only way to clear was to power off Mac mini and restart. This became annoying as it usually powered up in recovery mode which required a reboot to clear even if rebooting from the apple menu.

This seems to happen every two to three weeks of operation.

This weekend the BENQ monitor behaved a bit erratically and start showing what looked like static, after about 10 seconds it corrected itself and operated normally. I presumed this was a monitor problem.

This morning the same thing happened, the BENQ displayed static, for a few seconds, but instead of going back to normal it became green with a black mouse cursor which could be moved around.

Removing the HDMI cable moved the screen over to the LG, but re-inserting the HDMI to try to return to dual monitor caused the LG to stop showing any image.

I then tried disconnecting the LG and moving the HDMI from the BENQ and plugging into the LG, this showed the same green screen with black mouse I saw on the BENQ, which indicates the problem was generated from the Mac mini.

No matter what I tried nothing would get any of the screens working, eventually both would no longer show any image. I tried holding the power button down to turn off, waiting 30 seconds and powering back on, but still no image on either screen. Eventually I had to power off, unplug power cable, wait 30 seconds, re-insert power cable and power on to resolve.

Maybe I will try a different cable for the LG monitor, but the green screen issue I had was definitely the Mac mini as it followed whichever monitor was inserted into the HDMI port.

I hope the next release does resolve this as it makes my move to MacOS quite disappointing.

Anyway, posting this here in case someone else has seen the same issues, or it helps identify the cause.

I would not buy the Mac mini again. Yesterday, it costs less than anew iMac. No, it remains unreliable.

i have had every failure described in the community posts. External tb drives unseen. Monitor fiascos. FileVault resets. Monitor flickering.

each time I start up, it is a crap shoot if it will work.

when I run it, it is risky it will suddenly blank out.

apple has not fixed this through 10.14.4. No idea if they will ever fix it.

if you want reliability, this machine is currently not acceptable.

since the failures seem to be intermittent, it will take days or weeks of use with 10.14.5 to assess if it has become truly stable.

if you have to buy tomorrow, buy the iMac and avoid the Mini.

I have been running 10.14.5 now "successfully" with two monitors for 2 days.

BUT

Today, for no apparent reason, the Mini "fell asleep" for no reason. At the time, I was editing a WORD document.

Both screens went blank (no video signal).

After about 20 seconds, the logon screen re-appeared, asking me to enter my password to start up

Upon startup, both screens were active again, and I had not lost a single keystroke in the WORD document,

About 1 minute later, the same thing happened.

About 2 minutes later, the same thing happened.

After 3 times, I did a complete shutdown, and went to lunch. The top of the mini was "hot" to the touch.

After 1 hour after lunch, the Mini is "cool" again, and it started up correctly.

So, on top of all the issues I have had with dual screens not working, external hard drives not being recognized, garbage showing up in the screens, request by the OS to undo FILEVAULT, etc. I now have random "shutdowns" by the computer that "might" be related to heat.

GRRRR

smcFanControl is free, open source, and quite effective and easy to use.

https://github.com/hholtmann/smcFanControl

I have used it on my laptops for years, mainly to avoid burning my legs!

That said, if you need to use it to avoid crashes, take your Mini back to the Apple store and have it checked out, because something is wrong. I have had no overheating issues at all. I tested using Intel's Power Gadget, also free.

The same issue I had (Dual monitors on mac mini 2018 do not turn ON reliable).

For me : both LG monitors on TB3 was no fun : with one on HDMI and one on TB3 is better AND still it fails on reboot (sleep seems to work). I've tried everything and it simply does not work reliable.

I have to add another step to this long and not good <Apple Story>. After a thousand other experiments, from some days I have add to my station built of 2 news monitors LG / 24 "(connected to the macmini 1 on HDMI and 1 on THUNDERBOLT), a third very old monitor (connected on THUNDERBOLT thanks to VGA / THUNDERBOLT adapter).

Even with some difficulty, this 3 monitors configuration seems to work better than before. Now the monitors also wake up from the stop <even!>.

When you start/restart or when you wake up from the stop, in the presence of multiple screens (2), MacMini do not recognize sequence to start monitors (first/second): monitors starts in confusing positions between them, often. So, if it is possible manually to teach to MacMini what is the <first monitor>, it could be a good solution (I'll try). The improvement that I found introducing the third monitor probably has to do with this boot logic, too: Does the presence of the third monitor better inform the MacMici about monitor position (close the circle of possibility)? Third monitor reduces the chances of error, but does not completely eliminate them. Any case, after all this, two questions I have: Apple what are doing? Why must we suffer from his negligence?

I couldn't find the switch you referred to, but it occurred to me one could just use a $11 USB switch (incorrectly sold as a splitter!) to do the same thing, e.g. https://amzn.to/2XD0Ipv or https://amzn.to/2XJtuFe

I am trying shutting off NightShift to see if it helps the monitors wake up faster—wake up from sleep is absurdly slow at the moment (around 10-20 seconds)—as someone else suggested.

Come to think of it, using a switch might help with troubleshooting between the two displays... what I've been doing is manually disconnecting one display which has a USB-C-to-HDMI connector.

Using an AOC 32" 4k monitor (which works swimmingly with my 2015 MBP) with formerly fabulous 2018 Mac Mini:

• Purchased on November, worked fine until a month or so ago. Connecting TB3 to HDMI.
• Beginning a month or so ago I had an issue starting up wherein it would take me directly to Reset Password, which my wireless mouse was useless for and wired keyboard couldn't get me out of. Physically turning off, then doing a PRAM reset seemed to get me around this.
• "No Signal" to monitor began shortly thereafter - for whatever reason switching to a different TB3 port worked.
• "No Signal" to monitor began happening upon every restart. Switching TB3 output stopped working. PRAM reset stopped working.
• Purchased Sonnet Puck EGPU (directly from Apple.com, so, like, compatibility assumed) yesterday thinking this would fix the issues, along with making Adobe graphics (I gots prototypes to make!) programs less choppy.
• Currently: After attempting various methods of connection (only thing I haven't tried is HDMI to HDMI, but if that's the only thing that works my $400 egpu is useless) the best I can get is an Apple icon with load bar for about 10 seconds before signal is lost again.
• Have not tried disabling FileVault because I need to actually see a UI for that.

Hey, Apple, you know the Mini depends on an external monitor for basic functionality/usability, right? That's, like, the very base of the user experience pyramid - being able to use the goddamn thing.

Do you have the IPS version or the TN? I have the IPS version AC27XB271HUBM. I have issues as well. HDMI port not working at all. Using a cheap usb-c to hdmi adapter. It works most of the times. But not from cold boot. Have to the pull the cable in and out.

Also deep sleep it's not waking from. Have to push the on off button on the monitor to have it wake up.

The Apple original usb-c to hdmi adapter is not working at all for me. As bad as the built in HDMI port.

Will try to disable deep sleep mode. But I think I allready have tried that.

I have tried around 7 different monitors at work. Half of them have issues with the Mac Mini 2018.

when I first bought my 2018 Mac mini (purchased in Dec 2018) I had an awful time connecting to the usb-c connection on my dell monitor. Eventually I had to give up. Had all sorts of issues coming out of sleep mode and from a cold start. Eventually I had to go to the hdmi connection. This worked pretty well for the past 5 months. Recently my sleep or cold start issues started all over again. On a whim I plugged the monitor back to the usb-c cable. Problem fixed. Must have been one of the OS X updates that fixed usb-c but then hurt hdmi. Either way.... as long as one of the connections work....

I'm in the [cold start - no signal - entering power saving mode] camp.

Taking a look at the install.log file, I can see this started for me after installing macOS 10.14.5. Before getting a 4K monitor I was using a Samsung TV (UE43J5570SU), which is Full HD but not 4K. I did Xcode development without any issues on macOS 10.14.1, 10.14.2 and 10.14.4 using this setup (since November of last year).

After installing macOS 10.14.5 last week, I noticed the issue with the Samsung TV. I thought it was a TV issue and forgot about it, since I was getting an LG 4K monitor anyway (27UK850-W). This works beautifully with the official HDMI cable provided by LG in the box. But it has the issue, just like I had started having with the Samsung TV after 10.14.5. I couldn't test the 4K monitor in a previous masOS version to compare.

I also have to power off a couple of times until the "forgotten password" appears and then restart. After one restart, the Apple logo showed a blinking red-filled box around it, as the progress bar was increasing. That was weird, as in some kind of synching issue.

Hope this helps the engineers, the new 10.14.6 beta looks promising for some people.

I upgraded my Mac mini i7 to 10.14 6 a few days ago.

this afternoon, one of two monitors blinked black for about 10 seconds, and then re-appeared. This was after a long time of very heavy cup usage.

‘My mini already had one fan fail... apple replaced it.

‘’It seems the internals of the mini simply cannot reliably support two monitors . Whether it is a heat issue, or firmware, etc. I do not know. After 8 months of ownership and 20+ times that monitors failed, external hard drives do not mount, refusal to allow encryption of external hard drives, time machine failures, etc., I have had enough.

sorry, 10.14.6 has not cured the long saga of two monitors.

I bought a new i9900 dell computer today with a pretty nice video card.

$1700 including 1070 video, 16 mb memory, 512 gb ssd, 2 tb hard drive, lots of expansion options.

something similar iMac pro from Apple is $5000+ And still months away.

I have to get on, and the Apple Mac mini is simply not reliable as a high end workhorse.

sorry, the mini simply appears to be a poor design for heavy workloads with two monitors.

Apple has failed. Apple sold a product that does not work reliably.

Was anything specific mentioned in the Catalina update notes regarding this issue? I am having this problem with an LG Ultrawide 34" monitor connected by HDMI to Mac Mini (monitor inconsistently sensing signal from the Mac upon startup).

Sometimes double-pressing the power button on the Mac seems to get it to send signal to the monitor.

In my case this is Mac Mini 2018 i7 and Eizo S1921 monitor. Disabling File Vault, neither upgrade to OS X 10.4.6 helped anything. I have 10 days left to return Mac Mini getting money back. It the problem is not solved during that time - e.g. by Catalina release - I will send Mac Mini 2018 back to the shop for get my money back.