Underscan slider missing in Display set-up window

I know this is an old thread but in case someone else has the same issue still I realised that my monitor has two options for input via HDMi (HDMI VGA and HDMI PC) When I select the PC everything scales correctly. However the underscan still isn't there which is a pain but it did solve my problem. Side note I am running this display through a thunderbolt 2 port to a HDD daisy chained to a Elgato dock and then to the monitor. That might be why I am not seeing the under scan option????

Yes, we do need to use under scan. I have an HP 2310 monitor. It interprets HDMI inputs as a television signal and applies overscan to the image, causing the outer edge of the display to be cut off. On MacOS, it means the dock and the menu bar are out of frame and you cannot see them.

This is why the under scan adjustment was crucial, and no amount of fiddling with the other options on the MacBook resolve the issue, and the monitor itself has no option to turn off the overscan setting.

So the option is to use my $2800 MacBook in a non-native setting to the display, or scale down to a lower display and have an enlarged black order all around the display. Neither option should be acceptable for the cost of this machine, especially considering the adjust was available before.

I found a solution for those who have low-quality TVs which, like my own, may not allow you to turn off overscan in their own settings.

While the slider is gone Displays preference panel GUI, the preference itself is still accessible and editable in a file. It's stored in /private/var/db/.com.apple.iokit.graphics, and you can edit it as long as you have administrator privileges. I, personally, opened it on vi (because TextEdit was refusing to open at all with sudo, something which I really don't understand because it used to work fine in older versions of macOS), by opening Terminal and inputting the command:

sudo vi /private/var/db/.com.apple.iokit.graphics

Then it was only a matter of editing the value for the property “pscn” (to start editing text in vi like in a normal GUI text editor, just press A and use your arrow keys to change your insertion point – or vice-versa, it doesn't really matter which one you do first), which will appear like this:

<key>pscn</key>

<integer>10000</integer>

By the way, I'm not sure whether these were a leftover from back when I still had the slider, but if they aren't there, you can always try to add them after these other two, like so:

<key>framebuffer-rotation</key>

<integer>0</integer>

<key>pscn</key>

<integer>10000</integer>

Please bear in mind that you will have at least two monitors in that file (your internal one and the one you're trying to adjust), and maybe even more (in my case, I also had what was probably a leftover from a projector I connected my Mac into for some lecture presentations I gave at my Uni), so if none of them has that “pscn” tag present, you may have to figure it out by trial and error (and since the rest of the tags aren't exactly human-readable – seriously; you'd expect to see some brand names and models, but it's mostly gibberish – I have no idea whether you can underscan your internal monitor without ill effects, so do it at your own risk).

Anyway, I digress… “10000” is the baseline value, meaning it won't be underscanned or overscanned. Any value under that (in my TV's case, even though I didn't get it pixel-perfect and it still looks a bit analogue video-ish, I eventually figured it was around 9530) will underscan the output and, conversely, any value above it will overscan it even further.

So, just try a value, exit vi while saving the file by pressing the Escape key, followed by semi-colon, X, and Return/Enter. Reboot, see how it turned out, and if you didn't nail the value right away, give it a few more tries until you narrow it down.

Oh, and finally, I'm not sure if this is really necessary, but I believe that at my first try the changes I did to the file didn't really stick after rebooting. I changed that file's permissions to be read-only for all users (including “system”) before rebooting, and changed it back to read & write everytime I had to edit it again. Eventually, I stopped bothering about changing it back and forth between reboots, and the new values I was trying were always sticking after all.

Hi,

You shouldn't have to use underscan, and I don't know what they might have done with it in Sierra (I'm on El Capitan). Try clicking not the Scaled button and choosing the display's native resolution (1440 x 900?) or see if a different one works.

Sorry I couldn't help. Perhaps someone else will stop by with a solution (or at least state whether or not they have the Underscan slider in Sierra).

Meanwhile, I would try resetting NVRAM, SMC, booting into Safe Mode, and creating a new admin user account to see if it works there. Who knows?

I do not recall the specific update which caused the disappearance of the underscan bar, though I think it has been two or three months - maybe more. I have really not found a solution using the macbook. Though, what I did was to go directly to my monitor's settings and change the display size. I believe your monitor will have a display size and ratio that fits your macbook's ones.

Though, I would very much like the undercan bar to return.

Facing similar issue, although the underscan/overscan slider was visible just a few months back on the same external display. Perhaps there should be away to request Apple to revert those changes with an update.

As a workaround, I am using SwitchResX application to manually adjust my display but it ll only work for next 10 days and I have no intention to spend extra bucks for a simple underscan/overscan issue while it can be a should be a part display setting...

😟

Hello,

I was having the same issue after connecting the newly bought USB-C to HDMI adapter to my late 2016 Macbook pro w Touchbar: there is no Underscale bar in the Display settings.

For me, the solution also was to go into the settings of my HP Pavilion 22xi monitor and turn off the Overscale feature (default setting is on Auto, and it overscaled in my case).

Thanks for the tip, akegkeroglou!

I have a Hannspree monitor that worked perfectly with my older MBP using the display port to DVI port. With the new 2016 MBP, I bought a USB-C to HDMI. I couldn't see 1/4" or so around the edge. So, no top menu and full screen on apps means is problematic. I found in the monitor settings that I could change from "Video mode" to "PC mode." For me, this solved the problem. I only add this in case others have a similar setting. I also think the underscan slider was a better, more flexible solution.

My large screen RCA monitor has no adjustment to turn off overscan, either. My eyesight is failing, and I cannot see the screen without the large monitor. The menu bar disappears off the top of the screen. What are we supposed to do? Go back to El Capitan, where everything worked? Become developers so we can roll-back the OS to the point where it once worked? This is as frustrating as it was in the beginning when OS X monitor screen scaling wouldn't work unless you rotated your screen. Did Apple make it impossible to use these 3rd party large-screen monitors on purpose? Will this problem ever be fixed (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.

HP Pavilion 25xi Monitor to set the Overscan / Underscan. I'm using an HDMI cable to my mac mini . I tried both the DVI and HDMI to see if it would automatically reset, but it doesn't. So, I'm choosing the HDMI cable. Peeps, as far as I know this works only for the HP Pavilion 25xi Monitor. You'll need to consult the directions for your monitors to see where you can adjust this. Right now, with the latest version of OS you there is no bar to adjust this from your mac

Go into your monitor HP Main Menu, These are the controls for the monitor

Use the up and down button. Go into Image Control, Select Custom Scaling, Select Underscan, SAVE before you exit.

Apple Support - why did you do away with the under/over scan bar in displays? It made our lives so easy! Now we have to go outside our apple world to make modifications for 3rd party hardware to work.

I had this problem with HDMI on my ViewSonic VX2735. This monitor has two HDMI ports and one 15 pin VGA port. I use the Oversscan slider to make the picture smaller to fit within the monitors bezel. The Overscan slider disappeared with High Sierra.

However, reading all of the replies here, someone mentioned a PCMode option. It's not in High Sierras' Display preferences, so I thought, maybe there's a switch on the back of the monitor. There isn't. But there the two monitor ports are labelled HDMI1 and HDMI2. I had been using HDMI2. When I switched to HDMI1, the Overscan disappeared. So it looks like one HDMI port is intended for PC and the other for TV.

Been scouring the forums to solve this problem with no luck. Ended up pulling out an old DVI to HDMI adapter I used with the display port adapter on my old 2008 MBP and it worked!

One of the reasons I bought a new MacBook was to channel audio and video on one cable, so thank you Apple - the HDMI standard now ***** on your platform. Perhaps you should roll back USB 3 support, or uninstall sound in your next update.