Intermittent snowy screen when waking up Mac mini

Storm312

macrumors newbie
Original poster
Nov 10, 2018
20
10
Getting this randomly when I wake the new Mac mini:


If I unplug it and plug it back in, the screen returns to normal. Connected via HDMI, no dongles.
Is anyone else getting this? I've seen this problem with a coworker's MacBook Pro at work, so I know it's not isolated. I thought this was fixed in Mojave...
 

michaelb5000

macrumors regular
Sep 23, 2015
106
55
I get this too when waking from sleep with a display hooked up via HDMI (mine is solid snow without any lines or bars, but that may be an artifact of your picture).
 

Storm312

macrumors newbie
Original poster
Nov 10, 2018
20
10
I get this too when waking from sleep with a display hooked up via HDMI (mine is solid snow without any lines or bars, but that may be an artifact of your picture).
No artifacts, that's exactly how it appeared.
 

StellarVixen

macrumors 68000
Mar 1, 2018
1,990
3,254
Earth
Try to rotate the antenna a little bit, it helps.

Jk, I had something similar to this, when I wake up my MBP from sleep, but it is very brief, doesn’t even last a second. It has gone now.

I’ve thought you might be experiencing something similar, but this looks so different.
 
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rmdeluca

macrumors 6502
Oct 30, 2018
250
391
Don't you just love HDMI and, especially, HDCP? That's almost certainly an HDMI syncing issue. Assuming your cable isn't at fault (note: being new or having worked before doesn't guarantee it isn't at fault), this is usually one of those annoying issues where one or both ends of the connection are technically in-spec, but one of them doesn't think the other is. So it refuses to sync and you just get undecoded digital noise.

Test your cable by trying another one that is new and HDMI 2.0 (or better) compliant. The shorter the cable, the better. If that doesn't work, complain loudly because obscure HDMI sync issues like this are common but not easily resolved by the end user when the cable isn't at fault.

Good luck, I feel your pain :/
 

Storm312

macrumors newbie
Original poster
Nov 10, 2018
20
10
You might be right. I did borrow the cable from something else, didn't buy a new one. Unfortunately my cable doesn't have the version printed on it (just "High Speed HDMI"), but I haven't had issues with it with other devices. It's also pretty short. Wishing every cable clearly stated the spec... sounds like a support nightmare.
 

SoCalReviews

macrumors 6502a
Dec 31, 2012
580
199
You might be right. I did borrow the cable from something else, didn't buy a new one. Unfortunately my cable doesn't have the version printed on it (just "High Speed HDMI"), but I haven't had issues with it with other devices. It's also pretty short. Wishing every cable clearly stated the spec... sounds like a support nightmare.
I've experienced this before. It looks like a loose HDMI cable. Sometimes just unplugging it and re-inserting the cable into the back of the computer and/or monitor solves the problem. If that doesn't work try using a newer high quality HDMI cable. I like Wirelogic brand Sapphire HDMI cables. They are high quality and relatively inexpensive (You can get them for as low as $15 USD for a pack of two 12ft. cables at membership discount chain stores.)
 
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MacWorld78

macrumors 6502
Jul 25, 2012
426
181
I got similar issue I think - when I clicked on Apple Logo > Sleep > I end up like this

Black Screen for a second and then showing up white noise like you usually see on the TV (white snowy) then back to Mac OS, it won't sleep ?

do I have the wrong HDMI cable? I'm currently using "Nintendo Switch" HDMI cable lol to my Eizo CG2730.

Apart from sleep issue - everything else is working just fine...

Any advice would be great?
 
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rmdeluca

macrumors 6502
Oct 30, 2018
250
391
I got similar issue I think - when I clicked on Apple Logo > Sleep > I end up like this

Black Screen for a second and then showing up white noise like you usually see on the TV (white snowy) then back to Mac OS, it won't sleep ?

do I have the wrong HDMI cable? I'm currently using "Nintendo Switch" HDMI cable lol to my Eizo CG2730.

Any advice would be great?
The Nintendo Switch is a 1080p non HDR class device so it might not have come with a high speed HDMI cable. I can't see any markings on my Switch's cable to indicate one way or the other.

In your case I'd suggest trying a different cable or just get a USB-C to Display Port cable and dispense with the HDMI quirkiness altogether.

--

My suggestions for HDMI cables in general:

* Short as physically possible

* Rated for HDMI 2.0a (or better as new standards are released)

* Does not have a huge braided covering that adds a lot of mass to the cable. Why? Because the HDMI connector is idiotically designed with no lock so that it's very easy for the cable's mass or crimpiness to push one or more of the pins away from making a solid connection. Using a plain cable with the above criteria (such as an AmazonBasics) helps to reduce the chance of making a bad connection.

Source: about 15 years of designing and installing products in the home automation/theater sector. HDMI/HDCP is, to this day, one of the greatest points of failure.
 
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MacWorld78

macrumors 6502
Jul 25, 2012
426
181
The Nintendo Switch is a 1080p non HDR class device so it might not have come with a high speed HDMI cable. I can't see any markings on my Switch's cable to indicate one way or the other.

In your case I'd suggest trying a different cable or just get a USB-C to Display Port cable and dispense with the HDMI quirkiness altogether.

--

My suggestions for HDMI cables in general:

* Short as physically possible

* Rated for HDMI 2.0a (or better as new standards are released)

* Does not have a huge braided covering that adds a lot of mass to the cable. Why? Because the HDMI connector is idiotically designed with no lock so that it's very easy for the cable's mass or crimpiness to push one or more of the pins away from making a solid connection. Using a plain cable with the above criteria (such as an AmazonBasics) helps to reduce the chance of making a bad connection.

Source: about 15 years of designing and installing products in the home automation/theater sector. HDMI/HDCP is, to this day, one of the greatest points of failure.
Many thanks for the speedy reply.

Just wondering does the "USB-C to Display Port" support 10-bit display (display billions of colours)?
 

MacWorld78

macrumors 6502
Jul 25, 2012
426
181
Actually you are right about the Nintendo HDMI cable isn't up-to high speed HDMI, however I took out one my FireTV’s HDMI cable (AmazonBasics High-Speed HDMI Cable 3 m / 9.8 Feet Supports Ethernet, 3D, Audio Return 1.4).

Now it's working just fine no more “snowy/white noise” but I think this cable isn’t highest quality. No issue for sleep mode and wake.

My monitor Eizo (cg2730) accept 1.4 HDMI but do you think it worth to order more expensive cable like an HDMI 2.0 for the highest quality displays?
 

rmdeluca

macrumors 6502
Oct 30, 2018
250
391
Now it's working just fine no more “snowy/white noise” but I think this cable isn’t highest quality. No issue for sleep mode and wake.

My monitor Eizo (cg2730) accept 1.4 HDMI but do you think it worth to order more expensive cable like an HDMI 2.0 for the highest quality displays?
No, not unless you are still having problems. The reason why I usually recommend an HDMI 2.0 cable even if you're only passing HDMI 1.4 is that the 2.0 cable is just more likely to be able to pass 1.4 properly when you roll the "buy cheap imported cable" dice. However, once you find a cable that carries the full capability of your monitor (2560x1440@60Hz@10bpp) without issue, then you're good to go.
 
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wardie

macrumors 6502
Aug 18, 2008
320
94
Interesting... just managed to get my hands on a UK refurb 2018 mini i5 / 8GB / 256GB config. Trying it out with a temporary monitor which is old Apple Cinema HD display, connected via a HDMI to DVI-D adapter (although my final solution is similar). Screen works fine bur I just walked in after leaving it to sleep on default energy settings and I got the fuzzy white noise screen. Tapped a button and it went away. Very odd. Not a big deal as I tend to use it as a headless server anyway, but annoying. I've switched all the smart power settings and sleep / hard disk sleep off for time being. Still in return window but I'd be loathed to give up the discount I get on this it looks like v nice machine. IMG_2782.jpeg IMG_2786.jpeg
 

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