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External monitor flashes blue green red black while on standby

I have an M1 Mac Mini with Big Sur 11.4 and yesterday the external monitor started flashing white then red, green, blue, black when the computer goes to sleep. i.e. the whole screen is white, then red etc. I have restarted the machine, unplugged the monitor and disconnected the HDMI cable but it is still the same. Any ideas?

Posted on Jun 26, 2021 6:47 AM

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Posted on Jun 26, 2021 7:04 AM

What external display/monitor?

What HDMI cable?


Try a different Premium Certified HDMI cable.

4 replies

External monitor flashes blue green red black while on standby

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