display resize issues with mac osx high sierra waking from sleep

I changed the TV picture size (through the TV menu not the mac mini) from 16:9 to "fit screen" and then adjusted the underscan on the mac mini until it fit the TV display and it seemed to have fixed the problem.

Actually, simply switching on TV after Mac didn't work when restarting - it does work when waking up from sleep, but not for a restart - so if you shut your Mac down, you have to reset the TV underscan every single time you restart. Very annoying!

However, the 50Hz setting does work, whether TV is on or off when restarting, or sleeping. (I am in the UK, by the way, if that makes any difference? Any my TV is a Sharp.)

Thanks everyone, this was really bugging me, and the refresh rate setting seems to have fixed the problem!

I changed the TV picture size from 16:9 to "fit screen" and adjusted the underscan until it fit the TV display and it seemed to have fixed the problem.

After an excellent apple support, I solved it by setting Refresh Rate to 50hz Pal.

Also, try turning OFF overscan/underscan option in your TV/Monitor settings if available. Thus, I was able to solve this issue ( both restart and sleep mode ) with my Panasonic TV.

I have the same issue with a late 2014 Mac mini and High Sierra. I can confirm that turning the TV off and on again resets the underscan without needing to go into the OS X settings. I hope this is a simple (and quick) fix for Apple.

I had the same issue after upgrading to MacOS High Sierra, using a Mac Mini and a Viewsonic monitor. I unplugged the HDMI cable from the monitor and plugged it back in, and then the screen resolution remained correct even after the computer goes to sleep and I awake it again.

The same overscan issue occured after installing High Sierra update when using a Mac mini set up and a HP 23xi monitor. I've found the solution is to use the HP monitor controls (the bottom right buttons found on the monitor itself). Go into menus and find Image Control then Custom Scaling to switch the Overscan control from Auto to Off.

There doesn't seem to be a solution to be found from within the Apple software though a workaround is to go to Settings each time you logon, then to Resolution and select Scaled. Then select 1600 x 900 (which corrects the dimensions) and then select 1080p.

While this works for HP23xi and Mac mini (2012) it may be different for other monitor set ups, but if possible try addressing the display problem through the monitor's own controls and not the Apple software.

After an excellent apple support, I solved it by setting Refresh Rate to 50hz Pal for Panasonic TV. Check your TV type and set accordingly.

Thanks for this workaround, I just tried it out and it does the trick. It also works if you ensure you wake the Mac before turning the TV on. These two options will have to do until Apple fix the issue (which I hope they are aware of).

I have had the exact same issue on my late 2013 MacBook Pro ever since the High Sierra update. I found that the computer actually remembers the prior under scan setting when you simply click on top of the under scan slide arrow in system display settings. It immediately restores the previous setting without moving the arrow.(!) It appears that this is yet another sloppy mistake by Apple that should have been figured out before releasing the update. Hopefully, Apple's engineers can fix the issue quickly since it has become a regular aggravation to my work day.

I've got the same issue with my Mac Mini (Late 2012) connected via HDMI to a Sanyo Vizon.

I think there's a chance that Apple OS is no longer supporting some external monitors.

By the way, another way to resize the display is to unplug and replug the HDMI cable, pretty annoying...

I have a late 2012 Mac Mini connected to the Samsung living room TV and have the same issue. While changing inputs (e.g. to use the PS4) doesn't affect the underscan settings, turning off the TV and letting the Mac go to sleep overnight does. Every time I've turned off the TV and let the Mac sleep, same issue...

Turning off the overscan was the solution for my HP monitor (usually the default is set on Auto). But you must do it by using the monitor's own control buttons. Changing to 50Hz made no difference so perhaps this fix is either brand or country specific.

Even after adjusting sucessfully for the overscan, the Mac mini is more sluggish when waking up now. The screen is partly greyed out for a minute or so and the bluetooth mouse takes a couple of minutes to come back to life now.

This never happened before. It started with the last High Sierra update. Let's hope Apple takes note and puts in a fix.

I have this same issue on my late 2012 Mac Mini, after upgrading to High Sierra. It is connected to an HP monitor via HDMI. I also have the same monitor connected to my MBP (running High Sierra), via a USB-C to VGA adapter, and it does not exhibit the same behavior.