ASUS has horrible quality control. I purchased a PG278Q (TN panel) in Jan 2017, manufactured in July 2016 assuming I wouldn't have to deal with IPS glow. Ended up with a horrible power issue which kept restarting my monitor. Plus the menu overlay got corrupted with artifacts.
They tried replacing the panel (I donno why) and the issue persisted. So they offered me a total refund(Cos I think they know there is no workaround) and I gladly accepted.
In my personal experience, the PG278/9Q series are the best 1440p+GSync monitors out there, but only if you're lucky enough to not get a faulty piece of crap.