Can't output more than 1080p by HDMI

[Aldisa]

Hi.

A month ago I changed my monitors to 1440p (2560 x 1440p), 144Hz ones. I am not able to make the laptop (HP EliteBook 840 G5 with an Intel 620 Graphics Card) to output more than 1080p 60Hz by it's HDMI output. I bought a cheap USB-C > HDMI adapter and that reaches up to 1440p with no problem (60Hz, but since is my job laptop I don't care that much about refresh rates above 60).

I tried the latest drivers from Intel, latest drivers from HP, oldest drivers from HP, oldest drivers from Intel (this last one has the option to add custom resolutions, more on that later).

I tried the Custom Resolution Utility from Toasty, and with the oldest Intel drivers I get an option to add a custom resolution, but with 1440 it says "no bandwith avaiable" (it's a bug known but unresolved by Intel.

I tried changing my HDMI cable, the one that outputs 1440 though the USB-C also goes up to 1080p in HDMI, and the cable from HDMI in the USB-C adapter also reaches 1440, so it's not the cable.

Both screens reach 1440 resolutions in the USB-C adapter (and in other computers) from all it's HDMI inputs.

After one month I have no more ideas (the IT department in my company was useless in this regard because it only says to me that I "update my drivers"). 

Please, help me, thanks!

[Aldisa]

I have an update to this problem: Today I tried to boot into a Linux Live USB (In this case Manjaro KDE with free drivers) and both screens (the USB-C to HDMI and the HDMI from the computer) connected to 1440p (2560x1440) 60Hz directly, no problems at all.

So this problem resides in the drivers, or in the OS, not in the computer, the cable, or the screens.

I still have to make it work under Windows 10, as my job requires me to use it. (And the laptop is capable of working in this resolution).

Thanks.