Force (correct) ultrawide resolution on Monitor

Question

I have an LG Ultrawide monitor with a native resolution of 2560x1080, now paired with a Surface Pro 6 (SP6) running Windows 10 Pro x64 (I upgraded). I am using a Mini Display Port to HDMI adapter for display, via the Surface Pro 3 Dock.

The problem:

I cannot get the SP6 to give any ultrawide resolutions. The highest it gives me is 1920x1080.

Originally the SP6 did not detect the monitor's brand and read it as "General PnP". After manually installing the driver from LG's website and the updating it via Windows, it is now recognized as "LG Ultrawide".

My Surface Pro 3, which was sold last year, worked fine with this setup.

More random things:

1. The same happened fresh out of the box with Windows 10 Home.
2. I am up to date with Windows 10 Pro.
3. I have tried the MiniDP on both the SP3 dock and machine.
4. Intel's website says I need to update my UHD 620 Graphics. Windows says it's up to date. Trying to install it anyway gives an error to the effect of "This is not for your machine".

Thoughts...

• It could be my adapter. But it worked fine for my SP3.

• My Thinkpad Yoga L380 works fine via HDMI, so likely the problem is not the monitor.

My Question:

I did order a new cable (MiniDP to DP) to try, but would like to try and get this figured out. Any way to force the resolution, or other ideas?

Edit: Display settings

Solution

It was the adapter. After installing the MiniDP to DP to my monitor it worked right away, both in the Dock and direct to the computer. I won't accept this answer because I'm still wondering why all was fine on the SP3. I may pick up a used SP3 or find a friend with one to retest.

Comments

[harrymc]

In Windows Settings > System > Display > Advanced display settings > your display > Display adapter properties > List All Modes, is the mode of 2560x1080 listed? If yes, can it be selected and OK?

[David P]

@harrymc It is not listed there. Only up to 1920x1080. I looked at the inf file, and 2560x1080 is the max resolution there. I'll edit with pics

[harrymc]

Are you using an HDMI 2.0 cable?

[David P]

Yes, I am using an HDMI cable ("Twisted Veins") which claims "Supports HDMI 2.0b 4K 60hz HDR on All Tested Devices Except Apple TV 4K Where it Only Supports 4K 30hz". I use the same cable for 4k/60hz on my HTPC. So I'm back to probably blaming the adapter. Not sure why it worked for SP3 though.

[harrymc]

The difference could be in the SP3/SP6 display adapters, which are different in both the hardware and the driver. DisplayPort should work fine.