2nd display recognised but black

[JessUK98]

I’m trying to get my laptop hooked up to my new monitor via HDMI, but having some difficulty.
It detects the monitor in the display settings, but doesn’t show anything on the monitor, it’s just black.
I’vew updated the display drivers, and changed the colour profile, but still had no joy.
Any ideas? It’s an old HP Pavillion laptop, and the monitor is 4K, so don’t know if that’s the issue. My old monitor was 1080p and connected fine. I’ve used a couple of different HDMI cables just to make sure as well.

[kempiejon]

You've tried the obvious Windows button and P check duplicate/extend settings. Try 2nd screen only. Or resolution conflict? Though that wouldn't usually be just black. From the desktop right click and from display settings try some different numbers.

Do you have another HDMI device you could try on the monitor just in case it is broken out the box a DVD player, freeview box or something?

[JessUK98]

Tried the Win & P to no avail.
I've dug out an old monitor that's 1080p and it works with that. Confirms HDMI port on laptop still works at least. So must be something to do with the other monitor being 4K?

[JessUK98]

Not to worry, I've just figured it out, the active signal resolution of the monitor was showing as 3840 × 2160 so I went into the properties and changed it to output to 1920 x 1080.