That's not the problem, HDMI 2.0 supports up to 144Hz at 1440p. The problem is that nVidia cards can't properly use Freesync when connected via older HDMI standards.
I can’t select freesync on any of my screens when connected to the HDMI port. So this is definitely a problem on the HDMI port of the card. I just did a test with 1 screen in AMS2. Freesync on, 70Hz in the settings, variable Vsync in NCP and all settings in the game maxed out. Wow what a difference. Beautiful GFX and runs so smooth. Understandable of course. 2560*1440 = 3.686.400 pixels. That is 1/3rd of the 11.059.200 when play 1440p on triples. But I think I’m gonna look for an ultra wide screen after all. As said before, I’m not a hardcore simracer, I play other games as well. So an ultrawide is the best option for me. I miss some FOV of course, that is a bit of a drawback but I win better GFX and a smoother experience. I have seen a couple of vids on racing with ultrawide screens and the FOV is higher than on my single 16:1 screens. Ever since I bought these 1440p screens I’m trying to get the best and smoothest experience. I have enough of all the tweaking.
On an AMD graphics card, 4k 60Hz Freesync monitor, the following works perfectly for me: - RTSS FPS limit at 58 (RivaTuner Statistics Server). - Freesync on. - V-sync on (in-game). - Standard Radeon profile. The picture is perfectly smooth and I have no noticeable input lag. Every other combination I find messes either with the smoothness or the FFB. I got the idea from watching Battle(non)sense videos on input lag and smoothness and reading Blurbusters articles. The idea is that you want both Freesync/Gsync and Vsync active by limiting FPS at -3 from your monitor maximum refresh rate (non-overclocked). It's so good that I see no point in getting a higher Hz monitor. It's much, much smoother than 144 Hz with bad settings since the frame times will fluctuate causing stutter. Input lag is clearly higher when V-sync is on and FPS approaches, gets at, or goes beyond, my monitor's maximum refresh rate (60 Hz). This can be seen without any fancy measuring equipment by comparing your physical wheel with the virtual.
I have bought an ultrawide 34inch 165hz screen. Works perfectly. No more triple screens for me as I’m not a hardcore simracer and play more other games than racegames lately.