iMac with second monitor freezes after sleep

[CurtL5]

Just joined hoping to find an answer...

I've had a 27" iMac for a year or so now - never had any issues... runs great.
3.2GHz Intel i5
24GB RAM
OEM AMD Radeon R9 M390 2GB Video Card

I just added a 32" HD TV as a 2nd monitor and as long as everything is up and running, it works great.
Not quite the resolution of the built-in but adequate.
As soon as the system goes to sleep, it freezes and will not wake. Only solution is to manually hold the power button until it completely shuts down, then fire it back up. If I unplug the second screen, it works fine.

Did some searching already and found similar probs with MacBooks and it was resolved by unticking the Automatic Graphics Switch option, but in this desktop, there are no options for this with only a single graphic option.

Other possible solutions seem to all revolve around Macbooks and not desktops.

Ideas? Fixes? Just doesnt seem that this is a standard feature!

 

[hobowankenobi]

Sleep has always been a tricky thing we take for granted, until it doesn't work...most often with external hardware variables. Usually it works as expected, but there have been exceptions for years....decades.

What happens if you shut the TV off...before sleep, or after sleep starts?

Is the machine/OS and drive sleeping, or just the display?

What else is plugged in?

....It may be there is no fix. I have seen a few models (many years ago) that would not sleep/wake with external monitors and other items plugged in.

 

[CurtL5]

Yes - thanks - I rather suspect it's coming down to that. I've tried various configurations but without success. Except of course, to physically remove the HDMI or power from #2 which isnt exactly practical.

On the advice of my utility company, I've simply unwound the sleep function and gone to monitor and HDD shutdown.
(not really but you get the idea... )

Sleep has always been a tricky thing we take for granted, until it doesn't work...most often with external hardware variables. Usually it works as expected, but there have been exceptions for years....decades.

What happens if you shut the TV off...before sleep, or after sleep starts?

Is the machine/OS and drive sleeping, or just the display?

What else is plugged in?

....It may be there is no fix. I have seen a few models (many years ago) that would not sleep/wake with external monitors and other items plugged in.