Just finished assembling a computer today (i7-8700k based). The U2718Q was working fine with it. After a few windows updates and a restart the monitor comes up and shows the BIOS splash screen and then says there's no HDMI signal and goes to sleep.
If I disconnect the HDMI cable and plug the PC into another non-dell, non-4k monitor I see the PC video. If I plug the U2718Q into my Mac Mini HDMI, I see video.
Somehow I'm guessing the Windows 10 update messed up settings somewhere. I'm using the internal motherboard video, but it's a bit of a catch22. Can't play with the dell settings if it's not plugged in. Various power cycles and HDMI connections/disconnections seems to make no difference.
Any suggestion on how to move forward?
Using the non-4k monitor, you can try to reinstall an earlier version of the onboard GPU driver from the motherboard manufacturer. As to how to stop Microsoft from pushing a newer driver, ask the Windows 10 users on that board.
Thanks for the reply. I tried to re-install the drivers from the mb manufacturer (ASUS) and also updated the bios but still nothing.
Last night I was able to get the monitor to work somehow, but the pc thought the dell 4k it was the non-4k ASUS monitor and allowed me to display (scaled) at 1920x1080 on the 4k monitor. Really strange. After the driver reinstall and the bios update it's back to not working.
I'm getting a DP cable today and will try to use both monitors at the same time (ASUS via HDMI and Dell via DP) and see if I can get drivers loaded.
Continued suggestions welcome.
The problem was the driver. I made the mistake of downloading the driver from the ASUS MB site and not checking the Intel site. The latest version, Version 15.60.01.4877 (dated 12/7/2017) for the Intel UHD 630 graphics fixed the problem. Hopefully further driver incantations get tested with this combo before being released.
Thanks to everyone for help.