Hello mate.

You should get 100 FPS with maxed out settings. I get 60 FPS maxed out with my 1070.

You have then newest drivers, good, but are your Nvidia settings correct ? Have you checked in the NV Control Pannel if something is wrong, maybe reset to default ?

Does the game really uses your GPU at full potential ?

Have you checked the CPU and RAM usage ?

Cleaned up registry base ?

Removed the useless applications that launch at start and works in background ?

Have you checked viruses ?

Something else that messes up really hard and that we very often forget is Windows. Are your updates done ?

I know that what I said are probably basic things that you already did but anyway I'm trying to help.

Ryzen R5 with a 2070 and I get 60-90fps on Ultra @ 1440. You have something very wrong with your system, apparently. If yuou figure it out please post your fix as others may be having the same issue.

Do you have more than one display connected to your PC?
I'm running the game also on 1440p with an i9 9900KF, 2080TI and I have no problems.
I use 3 displays and had some weird problems, when only one of them was running on 144hz and the others have been running with 60/70. Now, with all of them on 144hz I no longer had these frame drops.