ASUS monitors seem to have an issue where the back panel can overheat and burnout, that's what they fixed. While the ASUS techs were fixing that issue I borrowed the Dell monitor I mentioned. I just got my 'fixed' monitor back and now it's not being recognized by my PC, hopefully that clears up what I'm talking about.
Well I'm getting the impression that the fixed monitor is not really fixed. And who knows if you have the same monitor maybe they dropped some other monitor's innards into the frame.
I've got a Dell monitor U2312HM and it is the best monitor I've owned. It's 1080p I've decided not to upgrade to higher res or refresh because it's hard to get a piece of gear that just does what it is supposed to and does it for a long time. I've had this 5 years it must be getting over 20,000 hours.
With stuff like you're experiencing I eventually reach an aggro point where I'd rather spend more money on something else and move on. If the other monitor was working on your build get yourself a dell and have done. I have thrown what looks like "new" or "good" equipment out just to get it out of circulation and making people's lives miserable.
So say I'm having these issues and a guy lent me a dell and it works that begins to look pretty good compared to waiting for repairs installing drivers posting on fora and still, at the end of the day, not having a working monitor. So in that situation I'd say well maybe I should get me a Dell and eat the loss. That is essentially what happened on my RX 590 graphics card. It was the third one in just a few weeks. I felt that I was incompetent and didn't know how to install a graphics card properly. Eventually I gave up, bought a 1660 TI and it installed easy and works perfectly (at least for now). Turns out I know how to put in a graphics card after all. So I paid about $550 for a $300 graphics card because I have, into the bargain, a worthless brand new Sapphire Nitro RX 590.
It looks like you might be getting to that point with your ASUS monitor.
The reviews on Newegg are borderline for me. My ideal gear has a combined Newegg 5 and 4 rating of 90% or greater. 85%, which is what it is for this unit, means possible problems. It's a popular model however because of price and manufacturer rep I guess. There are a lot of references to problems with Displayport and backlighting.
https://www.newegg.com/p/N82E168242...278Q&cm_re=ASUS_VG278Q-_-24-236-821-_-Product
I will add that for many products it's VERY DIFFICULT to find 90% + ratings including motherboards psus monitors and what have you. I was just looking at some Dells that do not meet my > 90% criteria. The 1660 TI I'm using DID meet that criteria and so far so good.
Greg N