Second Monitor FPS Lag

I have an ASUS VG248QE (144 Hz) and just got an ASUS VC239 (60 Hz), but I noticed that my second monitor has really choppy frame rates in all applications (including on the desktop). When I test the FPS I get readings of 60, but it feels like 30.

I have the 144 Hz monitor plugged in on DVI and the 60 Hz on HDMI, I've tried rolling back some of my graphics drivers through NVIDIA and uninstalling some programs that I thought might be affecting performance like Razer Synapse, but nothing has worked.

I tested the monitor on a laptop and the frame rate was fine and didn't stutter, so I don't believe it to be a problem with the monitor itself.

I have a GTX 1060 with 6GB and I read somewhere that low voltages to the graphics card can affect some of the display settings, so is it possible that there is something wrong with the HDMI slot on my graphics card that is causing this frame rate issue?

If not, what else could be causing this problem?