PC monitor not in full display

Motherboard: ASRock H81M-DGS
Processor: Intel® Core??i3-4170 CPU @ 3.70GHz ? 4
Graphics: Intel® HD Graphics 4400 (HSW GT2)
OS: Ubuntu 20.04.3 LTS
Monitor: Samsung SuncMaster 2043

PC monitor is cropped about 50mm on each side I have to scroll to see all the text on the display.
Display menu it shows the resolution is on 1024x768 which is very low for the scrren.
Checking in Settings -> Displays there are two resolutions 1024x768 (4:3) and 800x600 (4:3).
There no option to change the aspect ratio.
Searching for the fault found my other two HDDs one with Ubuntu 20.04 and the other with
Kubuntu react the same.
Tried other monitor and cable again react the same.
This happen in December last year I ask Ubuntu forums but after many tests there was no conclusion
to find the the fix the fault.
Search on the web dint find way to correct the fault.
I though it maybe the onboard graphics, the processor was Intel Celeron G1840 when this fault happen.
I replace the processor to the one above expecting to correct the problem.
But unfortunately no success it dint change a thing.
With all the test and changes I made come to conclusion the fault come from the motherboard.
Don't know where to start looking for the fault I turn to you people to help diagnostic and possible fixing this problem.
Thank you

Thank you to answer and help my problem.
I did that before and there are only two resolutions 1024x768 (4:3) and 800x600 (4:3).
This is my surprise of only two lower resolutions should be a selection of higher resolutions.

Test the monitor on other PC and on laptop both shown full displays on 1600x900 resolution and
it worked like before.
Connect back to Motherboard: ASRock H81M-DGS the screen again shows cropped and on 1024x768
Which is very difficult to work with it.
Is there away to check where the fault come from?
Is there something you can guide me to fix this I will very thankfull.
Samsung 2043SWX-1 Specs
Panel/Display

Type
LCD
Viewable Size
20"
Brightness
250cd/m2
Contrast Ratio
1000:1 (15,000:1 dynamic)
Viewing Angle
170° horizontal, 160° vertical
Pixel Dot Pitch
0.285mm
Response Time
5ms
Panel Life
Not Specified by Manufacturer
Colors Supported
16.7 million
Signal

Internal Interface
Analog/Digital
Frequency
Horizontal: 31-80kHz
Vertical: 56-75Hz
Sync Type
Separate H/V Sync, Composite Sync, Sync on Green
Resolution
1600 x 900
Input/Output Connectors

Analog
1x VGA
Digital
1x DVI-D
Audio Input
None
Headphone Jack
None
Hub Ports
None
Speakers
None
Mount
Desktop: Yes
Wall-mount: VESA 75x75mm
Controls

Buttons
Menu, Up/Brightness, Down/Custom, Enter/Source, Auto, Power
On-Screen Display
Picture, Color, Image, OSD, Setup, Information
Auto Configuration
Yes
Touch Screen
No
Tilt/Swivel Range
Tilt: Yes
Height: None
Swivel: None
Pivot: None
Security
Kensington Lock Slot
Compliant Standards
Energy Star, Class B
System Requirements
PC or Macintosh computer with VGA or DVI output
Power Requirements
AC: 100-240VAC (± 10%), 50/60Hz ± 3Hz
Environmental Requirements
Operating
Temperature: 50-104°F (10-40°C)
Humidity: 10-80%, non-condensing

Storage
Temperature: -4-113°F (-20-45°C)
Humidity: 5-95%, non-condensing
Dimensions
With Stand: 18.9 x 15.4 x 8.6" (47.9 x 39.2 x 21.8cm)
Without Stand: 18.9 x 12 x 2.6" (47.9 x 30.6 x 6.5cm)
Weight
With Stand: 9.9 lb (4.5kg)

Apologize to persist on this but since the fault was not found and I am working with extreme difficult resolution (Scrolling screen).
The problem is the display has two black strips about 50mm at both sides of the screen.
Test the screen with other computer and it work perfectly.
Replace the processor from Celeron G1840 to Intel® Core??i3-4170 there was no change.
I have three other HDD one with Ubuntu 20.04 other with Kubuntu 20.04 and other with old Ubuntu 16.04 they all work correctly before, booting with any of the HDD still shows the same problem.
I checked the web, checked the Ubuntu forms made different tests and come to the conclusion is not
software related, and it points to the motherboard
I turn to you people if some one knows what is the fault or knows how to find the fault let me know.
Is there a way to test this motherboard?
I appreciate some help on this.
Thank you