Dual Monitors - One Keeps Going Off and On

Patrick G

Limp Gawd
Jan 30, 2002
So I have a 2021 MacBook Pro hooked up to a StarTech dock connected to two identical Acer monitors via DisplayPort. All equipment is less than 6 months old, bought new. I’m having a recurring issue whereby the display on one of the Acer monitors goes completely black (i.e. goes off) for a couple of seconds, and then comes right back on. This happens multiple times per day. Sometimes I’ll reboot and the problem goes away for days, but more often, it comes back shortly after rebooting and continues off-and-on throughout the day. All drivers seem to be updated, and when I tried switching the two DisplayPort cables at the dock – so just swapped the monitor connections at the dock – that had no effect. The same monitor continued to exhibit the same behavior. So, I swapped the DisplayPort cable on the affected monitor for a brand new one. Same issue. At this point, can I assume it’s a defective monitor?
Defective monitor or defective startech adapter. I’d wager on the adapter if you already ruled out the cables.
Have you tried moving the connectors between the monitors themselves and not just at the dock? It's not likely but it's possible that both the old cable and new cable have issues.