Samsung C27F390 27inch monitor not working

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8 points

Samsung C27F390 27inch monitor not working

I have a Samsung C27F390 27inch monitor and I'm trying to connect it to my MacBook Pro 13 inch, M1, 2020 with macOS Monterey v12.5.1 through a usbc hub via HDMI. When I plug the monitor, it shows a message saying: Not optimal mode. Recommended mode 1920x1080 60Hz. The monitor already has this configuration. Also, in the displays setting, I tried to use every resolution option given in the menu, but none of them worked. Is there a solution for this? Is this monitor compatible with my Mac?

Posted on Sep 2, 2022 07:10 PM

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Answer 1

mingoslkd

Community Specialist

Sep 4, 2022 01:03 PM in response to JuanDGarayC

Hi JuanDGarayC,

Thank you for using the Apple Support Communities! For this issue, we would recommend the guidance in the following article that may help:

If your external display isn't detected or appears blurry when connected to your Mac

This section, specially, as the hub may be the issue here:

Check how many displays you can connect

If you're connecting multiple displays to your Mac, use the Tech Specs page to find out how many external displays your Mac supports.

1. Choose Apple menu  > About This Mac, double-click your serial number, then press Command-C to copy it.

2. Go to the Tech Specs page, click the Search Tech Specs bar, press Command-V to enter your computer's serial number, then click Search.

3. Click the specs page for your Mac. The number of displays your Mac supports appears under Video Support or Graphics.

As the Tech Specs page shows:

Display Support

Simultaneously supports full native resolution on the built-in display at millions of colors and:

• One external display with up to 6K resolution at 60Hz

MacBook Pro (13-inch, M1, 2020) - Technical Specifications

Hope this helps!

Have a great day.

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Answer 2

Sep 5, 2022 05:38 PM in response to JuanDGarayC

if you have accidentally or deliberately enabled [√} Mirror displays, then BOTH displays will be set to a compromise resolution that both appear capable of attaining.

Resolution can only be set separately when the displays are not mirrored.

.

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Answer 3

JuanDGarayC Author

Level 1

8 points

Sep 5, 2022 06:24 PM in response to Grant Bennet-Alder

Hi, I'm using the extended option. Here's a screenshot

With the other displays, it shows another dropdown list, the frequency rate. But, with this samsung monitor, it doesn't. I also tried with the Default for Display option, but no answer from the display, still showing the "Not optimal mode, recommended resolution: 1920x1080 60Hz."

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Answer 4

JuanDGarayC Author

Level 1

8 points

Sep 6, 2022 06:37 PM in response to Grant Bennet-Alder

Here is the Graphics & Displays screenshot:

The thing that I notice is that the 'UI Looks like' is running at 25Hz and it should be at 60Hz.

I've tried with the Terminal app Cscreen to set the refresh rate, but it wasn't possible. Also I installed an app called Better Display, set up the resolution and refresh rate, but nothing seems to work with this monitor.

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Answer 5

JuanDGarayC Author

Level 1

8 points

Sep 5, 2022 05:29 PM in response to mingoslkd

Thank you for your response.

However, I'm just trying to connect only one display. The hub is fine because I tried it with another two different displays, a HP display and a LG 4K TV. Both of them worked just fine, but the Samsung monitor doesn't work and it has the normal resolution: 1920x1080 60Hz, so I don't know if there are displays that are not compatible with this MacBook Pro.

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Answer 6

Sep 6, 2022 05:47 PM in response to JuanDGarayC

MacOS generally does not allow any display under about 3K resolution to run "scaled" resolutions.

When MacOS does allow Displays Preferences to show SCALED resolutions. These are NOT the Hardware resolutions you display is set to. These are effective resolutions for TEXT when displayed on that display when you select Scaled.

They are intended to be a convenience for you, but they often cause concern and outright alarm instead.

To see the ACTUAL resolution your display is set to use:

 Menu > about this Mac > (system report) > Graphics & Displays

Select your display and scroll around until you see two items.

The first is self explanatory: 'Resolution:' 2560 by 1080

This is the hardware resolution at which your display is operating. Graphics are drawn at this Actual Resolution. But there is a problem -- If text were displayed at the Actual Resolution, it would be microscopic and unreadable.

The second resolution shown is 'User Interface Looks like:' this reveals the apparent size of text displayed on your display after scaling is applied ONLY to textual items.

Text is rendered at full resolution, then SCALED by the display Hardware by a factor (like 1.2 or 1.5, or 2.0) before it is aded to the display buffer. This makes it fully readable, yet maintains crisp edges that would be lost otherwise.

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