This comment doesn't address your question directly but may help add to your thinking about other modes for using the monitor for future applications. I have the PA248Q too, and really like it = have found it to be an excellent monitor.
The PA248Q is supposed to be colour calibrated by Asus before shipping it out. Mine arrived with a printed form that showed all the results of that calibration; hopefully yours did too.
I use it primarily for photography and have set two custom "User Modes", which are the two I use all the time (rather than any of the defaults it came with): one is for when I'm working on images for web or screen use only (which is the one I use most of the time), and the other for images I'm going to print. The two modes look quite different: the Web one looks very much brighter than the print one - this is important for photo printing as otherwise I will be fooled by an over-bright monitor into thinking that my image is brighter than it really is, and it will print out too dark.
For the Web one, I have the colour temperature set to 6500 K, gamma at 2.2, and brightness at 25 (could probably go higher on latter but it seems easier on my eyes to keep it fairly low).
For the print mode I have the colour temp at 5000K, gamma at 1.8, brightness at 12.
Hue, saturation & contrast are also settable; mine are about the middle and I can't recall whether I set those myself or it showed them as default when I set up the user modes.
These seem to work well for my purposes. Not sure what the ideal colour temmp, gamma, & other settings might be for gaming, but some web searching would probably turn up some useful info on this. Good luck, and enjoy the monitor!