High Input Lag on Monitor Connected to Laptop via HDMI

[ccerreta1]

This is driving me nuts. Here are the pieces of the puzzle, hopefully someone knows what's up:

Alienware 17 Laptop, geforce 980m, i7, only video out is HDMI

connected to my old T27A300 monitor (1080p 60hz) there is no noticeable input lag
using the attached laptop screen, there is no noticeable input lag

I have a new BenQ PD3200U (4k 60hz)

playing games on the same settings (that is 1080p, even though this is a 4k monitor) I'm getting horrible input lag of a few hundred ms. There is a clear delay between the sound of a key being hit and the action occurring on screen.

I've tried using only the BenQ, and using it as a second monitor, same results.

 

[ccerreta1]

sort of figured it out ... my HDMI port is 1.4 which only supports 4k at 30hz. Something about that setup was introducing a ton of input lag (way more than you'd get from just capping the fps at 30).

Luckily I have a mini DP video out I did not know about, so I'm good, though if there's any way to remove the input lag and get a decent 30 fps by HDMI, I don't know