If it's HDMI 1.4 then it will only be able to do max 70hz @ 1440p, that what the XF270HUA (Zero Frame) was listed in the manual as the max it could do. So depending on the monitor it could be max 60hz if it doesn't have 75hz. It's why they included HDMI 2.0 it also had freesync over HDMI 2.0 but the overdrive didn't work with freesync.
I was able to output 144hz over HDMI on my XF270HUA. One HDMI port was HDMI 1.4 and limited to 70 hz, the other was HDMI 2.0 and could output 144 hz at 1440p.