Random short disconnects (HDMI)

[twoco]

I've connected my Mac mini M4 to my TV via HDMI. This is my only primary monitor. Since macOS 15.2 introduced the screen mirroring bug, I’ve set the TV’s role to "monitor". Works fine. The only problem is that I have to change YCbCr to RGB Full Range every time. But this is another issue...

My problem: Sometimes, my screen randomly goes black for a few seconds. Seems like HDMI disconnects. No idea what macOS is doing in the background, but it's definitely not right. Sometimes the screen is stable for hours and sometimes it flickers several times within an hour. It makes no sense. The HDMI cable and TV are perfectly fine and uses the latest HDMI version. This is not the problem. This is one thing I regret switching from Windows to Mac. On Windows the HDMI connection (same cable/TV) is perfect stable with full RGB quality. I suspect that this is a hardware error. I think this is more of a dumb-developer error from Apple.

Am I the only one experiencing this? Is there any fix? I can’t use DisplayPort. Nor should I have to, because HDMI should just work well. But somehow, Apple can't get it right. It already annoys me that macOS doesn’t use RGB Full Range. This forced limitation by Apple is beyond frustrating. The user needs a 3rd party "hacking" tool to change this. A great tool. But it shouldn't be like that. It's such an easy move if Apple would provide these basic settings. Anyway... I hope I can fix the random disconnects / black screens. Maybe by stopping some services in background?

[waydabber]

I think this is a rather common occurrence, I have it too from time-to-time on an M3 MBP connected to a Samsung 8K TV, but don't have it with M4 connected to a Philips 4K TV. Might be an indication of running things near the max cable bandwidth and sometimes some data error causes sync loss (?).

[twoco]

It's connected to a Samsung 4K TV at 60 Hz with a good 2.1 HDMI Cable which works with all other devices incl. PS5 up to 4k 120Hz. The default refreshrate is 120Hz at 4K. I doubt that this has to do with the bandwidth etc. It also does not matter if YCbCr or RGB. It happens randomly and independently of the screen content. Sometimes no issues the whole day. I hope this is not a hardware defect of the Mac.But I still think this is a software bug or bad software design. I mean, look how Apple handles the primary connected monitor when it's a TV connected over HDMI. Like a screen mirroring device for vacation slideshows. Apple really disappoints me in this case. And then I read stuff like "replace HDMI cable" or "don't use HDMI, use DP". That's pathetic. HDMI should work perfectly. Especially when it comes from a company like Apple, which sells such overpriced quality devices. It's annoying when the device isn't reliable. Apple should make macOS open source if they are too incompetent to implement it properly. I'm not sure if you've noticed yet: I'm a bit annoyed. :D

[IKIKN]

I reproduce the exact same issue, and it cannot be the cable, it's a brand new Ugreen cable that can go up to 4k@240Hz, but in my case, I'm not even hooked into a TV, but into a 2k monitor (Asus MX27AQ), so I'm not even in 4K.

My only theory is that in may be related to the refresh rate. BetterDisplay says that my refresh rate is 59.95 (not 94, 95!), and I think it should be 60:

Even if I press the "option" key when going into the menu and that 60Hz is displayed, it still displays 59.95Hz the next time I go into the menu:

Do you think that it could be linked to the issue, @waydabber ? Should I be worried?

Thanks!

[twoco]

My refresh rate is dancing between 59.999 and 60.002 Hz in the measurement. Under Display Information (Settings > Display), it shows 59.99999865889549 Hz. But the refresh rate is set to exact 60 Hz. I see also an option for 59.94 Hz, which comes from NTSC. But I don't think that this is a or the issue here. In my case I have very rarly black screens due to short disconnections. I think it's because something is checked or initialized in the background. But I don't know. What's you behavior? How many black screens do you have? Since no one can guess the problem, we have to do a successive troubleshooting by testing different cables etc. But I would guess that this has something to do with the Apple driver or some other software in the background. Maybe there is an event or error log which reveals the issue... In my opinion, Apple should provide such settings like BetterDisplay do. We only need this because Apple uses the primary connected monitor like a cheap device connected via screen mirroring for vacation slideshows, only because it's a TV connected via HDMI. At least in my case, it uses YCbCr Limited Range with GPU Dithering. I have a modern TV from last year which supports all known features, which I use as my primary monitor. It should use RGB Full Range and I recommend disabling GPU Dithering due to artifacts on dark areas. And change the role to "Monitor" instead of "TV". Apple should allow the user to change this essential settings, instead of doing wrong stuff in the background. Apple thinks that the single and only one connected screen device on a Mac mini is a secondary screen. Therefore Screen Mirroring is on, until you change the role from TV to Monitor. It's just a big fail of Apple. Because they know everything better than the user. It's not the user's computer, it's still Apple's property. You know? ^^ This issue really annoys me. Anyway... I doubt that this has to do with the refresh rate. Otherwise the problem would occur more periodically. In my case, I have hours or days without a problem. Maybe it depends on the weather. ;)

[IKIKN]

Hi,

Just as you, I reproduce the issue rarely (sometimes not even once a day, sometimes 2 or 3 times). From what I gathered on this Reddit thread, this indeed is a common issue and the only solution is not to use the HDMI output, and use a USB-C to HDMI cable instead (which is a pain because there are only 3 ports on the back...)