Anyone here good at troubleshooting external monitor issues?

[Robert]

I have a weird situation on a recently acquired Mac Mini I have twin monitors connected to. One is connected via USB-C to DVI converter lead & the other USB-C to VGA adaptor & lead. The VGA works as expected but the DVI has intermittent snow interrupting the display. It's about 8 seconds of normal display, followed by 2 seconds of snow and just repeats.
I had put this down to the cable being flaky and resolved to get a USB-C to DVI adaptor instead.

Then something very strange happened last night.

I had switched off the DVI screen but left it connected while I did some work in Logic via the VGA screen. I had been working like this for a couple of hours when I opened a window and it opened on the switched off screen so I had to switch it back on to see it.

For some as yet inexplicable reason, there was no snow and I was able to work with twin monitors for another 7 or 8 hours with no issue.

Alas, back to snow when I booted up this morning, despite my futile attempts to recreate whatever magical-faerie-dust circumstances resulted in last night's flawless performance, including leaving it connected but switched off for a couple of hours.

Anyone encountered such seemingly random behaviour before or able to explain it? If I can get an explanation of how to get it working like last night, I won't have to buy any more potentially unnecessary gear.

 

[Wayne]

I have a newer M1 Mac Mini connected to two 1440p monitors, but I can't say that I've experienced that issue. My dad, who is hooked to a single 1080p monitor, experiences a frozen up "white noise" static screen every once and again when he turns his i5 mini on, but I think that's more of a power management issue between the i5 and the monitor (which is connected straight through HDMI cables.

The only issue I get currently with the M1 is that when it boots up most of the time, or is rebooted, both monitors are mirrored to show the exact same screen. Turning my secondary monitor off, then back on usually resolves the issue though. I think in my case, it's more of a software compatibility thing which I'm hoping will eventually be resolved through patching.

I know it's kinda weird and some of you may be shocked, but I actually spent my own money on a Windows laptop (making my first microsoft-supporting purchase in over a decade.

Between black Friday, some credit I had built up at Amazon from returns and shipping errors on their part, and the fact that the laptop I bought was a refurbished i5 ASUS 15.6" machine, I literally spent $104 out of pocket, so hey, couldn't resist. It's now my maker station for 3d printing (managing my 3 printers) and my CNC machine.

Wayne