Can't fix underscan on Dell external monitor

[BikGer2]

Hello there,I just got a Dell P2422H display, and when I first plugged it into my m1 MacBook Air, it worked seamless, there was no underscan. However, after my Mac went to sleep and I woke it up later, the display started showing underscan. It makes it horrible to look at.

I tried a lot of ways of fixing it like:

Changing the resolution and refresh rate

mirroring the display

Safe mode

Tried using it via a test user account

plugging in and out the monitor

Searching through the display's settings

plugging Mac into an LG monitor that showed no underscan

Things to note: There weirdly is no underscan when I change to the following resolutions (1280x1024, 1152x864 and 1024x768). The display is connected with an HDMI cable through a Satechi usb c hub. There is Auto Adjust in the monitor's settings but according to the instruction manual, it works only for VGA.

I tried plugging in a Windows machine to the display and it worked fine. At this point, I just have no idea what to do.

Help much appreciated!

 

[Amethyst1]

Does macOS show settings related to underscan in the display’s preference pane (where you adjust its resolution)?

I’d try to connect the monitor via a USB-C to DisplayPort cable, or the hub’s DisplayPort output if there is one, next.

 

[BikGer2]

Nope, I have no underscan slider.
I could go out and get a usb c to DisplayPort cable, or perhaps a VGA Adapter to enable Auto Adjust on the monitor?

 

[Amethyst1]

Please don’t ever hook up a LCD monitor via VGA.
Auto Adjust is a kludge to help a digital LCD monitor “sync” to an analog (VGA) signal.
Use a digital connection such as DisplayPort for the best picture quality.

 

[BikGer2]

Ok, thanks for the advice, but what do I do with the underscan though?

 

[Amethyst1]

I’m hoping the problem will disappear using DisplayPort…

Have a look at the monitor’s settings — is it set to display lower resolutions at 1:1 or full screen? Playing with this setting is worth a try I guess.

 

[BikGer2]

I'll try playing with the display settings, I'll tell you if it works

 

[BikGer2]

So playing with the settings just didn't work. I checked out my local Apple dealer and they only have a direct usb c to HDMI 4k 60 cable. I think they don't even have display port adapters.
I have a Usb to miniDP cable that I found laying around somewhere, but my hub won't output video through usb.

 

[Amethyst1]

[...] my hub won't output video through usb.

Are you sure? What hub is it (can you provide a link)? Try connecting the USB-C-to-MiniDP cable straight to the MacBook Air (without the hub) to see if it works and you get a proper picture without underscan.

 

[BikGer2]

Here's the usb-c hub: https://satechi.net/products/satechi-slim-aluminum-type-c-multi-port-adapter?variant=27296854025
It's not actually a usb-c to miniDP, but a Usb A to miniDP cable. I should have pointed that out.

 

[BikGer2]

For some reason the reply I posted before this didn't get approved.
My hub is a Satechi slim aluminum multiport adapter.
The cable I have is not a usb-c to miniDP, but just a regular USB A to miniDP, I should have pointed that out.

 

[Amethyst1]

I’ve just checked Satechi’s multiport adapters: no video output via USB-C indeed.

[…] just a regular USB A to miniDP […]

That’s not going to work (and doesn't exist AFAIK, so you might have something else). In any case, you need a USB-C to DisplayPort cable.

 

[MBAir2010]

so that is the term for the image scaling on an external monitor, thanks!
the dell xps 13" had the problem, so i purchased a mac mini to entertain me!
i found this on 's website about adjusting under-over scans that might be helpful as well.

 

[Amethyst1]

i found this on 's website about adjusting under-over scans that might be helpful as well.

The slider doesn't appear for the OP, so no way to adjust it.

 

[DeltaMac]

It makes no sense to me that your Full-HD display would not show underscan on a non-native (and 4:3 on a 16:9 display) resolution, such as 1280 x 1024 (?)
If you set the external display for the native resolution - 1920 x 1080 on that Dell P2422H - how does the underscan appear?
Can you post a screenshot (with your external display connected) of your Displays pref pane, with the Arrangement tab showing?

 

[BikGer2]

I appreciate the help guys!
So I actually took the Mac to my authorized Apple dealer for them to check it out.
They didn't ask me to bring in the display though, I found that weird. They also told my to bring in my usb-c hub as they think that's the issue.
I'll keep you guys updated, should get it back until tomorrow.
I'm not able to really post any screenshots of the display prefs, it's all on my Mac.
By the way, I'm using the monitor hooked up to a windows machine via DP, and I can tell you it works great.

 

[Fishrrman]

What happens if you bypass the USB hub, and plug the display DIRECTLY into the MacBook?

 

[BikGer2]

Ok, so it worked out great.
I just picked it up, and the guys at the apple store basically told me they just plugged it into their display and it works.
They also told me to call their senior engineers if I face further problems, but that's not important right now.
@Amethyst1 I got a usb c to DP adapter and guess what, it works! Thank you for the help man.

I appreciate all of your guys help, the issue is solved!

 

[Amethyst1]

@Amethyst1 I got a usb c to DP adapter and guess what, it works! Thank you for the help man.

You're welcome. I know the "Screw HDMI, use DisplayPort!" solution sounds lame but... macOS and HDMI sometimes just don't play nice with each other.