Setting resolution - right way

I have really strange problem.

My Monitor is Asus ROG Strix XG49VQ with native resolution: 3840 x 1080. It is connected by Display Port to NVidia GeForce 1080Ti.

My Nvidia driver version is: 442.59
Windows 10 Home 1809

In Nvidia Control Panel In Change Resolution I have such Resolutions in two sections:

Let's focus only on FullHD resolution.

Section 1 - Ultra HD, HD, SD:
1080p, 1920x1080 with available refresh rates: 120, 119, 60, 59, 50 Hz

Section 2 - PC:
1920x1080 with available refresh rates: 144, 100 Hz

Questions and problems:

Why two sections? What is the difference between those two sections. I see refresh rate is different. When I set resolution and refresh rate from Section 1 then my monitor overlay (the overlay that is build into the display menu - firmware) is showing correct resolution. The picture is centered in the monitor in FullHD. Windows 10 "Advanced display settings" is showing 1920x1080 for "Desktop resolution" and "Active signal resolution". When I select resolution from Section 2 (PC) then my confusion get started so I will describe it now:

I selected 1920x1080@100Hz from Section 2 (PC)
- Monitor Overlay is showing: 2560x1080@100Hz - (why 2560?)
- Windows 10 Advanced display settings is showing:
Desktop resolution: 1920x1080
Active signal resolution: 2560x1080 - (why 2560?)
Refresh rate: 100Hz

I selected 1920x1080@144Hz from Section 2 (PC)
- Monitor Overlay is showing: 3840x1080@144Hz - (why 3840?)
- Windows 10 Advanced display settings is showing:
Desktop resolution: 1920x1080
Active signal resolution: 3840x1080 - (why 3840?)
Refresh rate: 143Hz

What I'm trying to understand is why changing 100Hz to 144Hz change "Active signal resolution" from 2560 to 3840 and why this resolution is larger than requested 1920x1080? I really don't understand if this is the driver problem, display problem or maybe just Nvidia Control Panel problem. I don't know how to diagnose this problem deeper because I don't know where to start. Maybe somebody will help me figure it out here.

Why when selecting resolution from Section 2 the Active signal resolution does not match Desktop resolution. Why when I change refresh rate only from 100Hz to 144Hz (in Section 2 for single resolution in both cases 1920x1080) my Active signal resolution is changing? I think Monitor Overlay is also showing Active signal resolution in my case. If this is expected behavior then can somebody put more light on it and explain why it is working like this? I'm really confused with this problem. I don't know what is the difference between Active signal resolution or Desktop resolution. I have also some problems in games because of this.

Waiting for help or more info in this topic... I can provide more information if this is required but for now I'm not aware what can be useful. Please take into account that I want to pick not native resolution but smaller one just for recording and publishing to Youtube some videos (and I want to record it in FullHD not in native 3480x1080).

--
Warm regards,
Marcin

 

Well its simple really the refresh rate you can get on your monitor is 120 max right. so the cable or monitor in question can not do 120hz @ 3840x1080 as the bandwith limitation probably cant cope with that resolution
so it gives you other options like dropping resilution so that you get 120hz refreshrate. or the other way around.

or it could be between the different options you get different color depth options.

 

This is 144Hz monitor connected via Display Port. I don't have any problems running it on native resolution 3840x1080 with 144Hz. It is definitely not bandwidth problem. I just want to reduce this resolution to 1920x1080 in some games. I don't understand why changing refresh rates change resolution. It seems that I can't control resolution but only refresh rate?