[SOLVED] Displayport issue

[Twigman893]

Yesterday I hooked up my lovely new Samsung Odyssey G9
It's sitting on a Displayport connection from my GPU (Gigabyte RTX2070 Windforce 2X 8G rev.1).
It will ONLY display if there is also a monitor also connected to the HDMI.
This is true in any of the 3 displayport ports.
If I disconnect the HDMI monitor nothing is displayed on the Odyssey via DP.
The HDMI monitor doesn't even need to be powered on but if I disconnect the HDMI (at either end) then the DP stops displaying.
In W10 Settings/Display the Odyssey (DP) is monitor1 and the other is monitor2. If I tell W10 to Display Only on1, it displays NOTHING.
I can only use the Odyssey if W10 is told to Extend these displays, even if display2 is powered off!
How can I get it so I only use DP?

WTF is going on?

 

[hang-the-9]

With the system shut off, disconnect the HDMI cable, leave in the DP port (if the card ports are labeled put it in the lowest numbered port), when you turn on the system do you see the BIOS splash screen? Does it have no display at all? Does the monitor power light change color form standby to on?

 

[Twigman893]

I got it sorted eventualy
On cold boot the BIOS was showing but on OS load the screen would go blank until I plugged in an HDMI monitor.!
Using the DDU driver removal tool in the sticky thread I cleaned off theold driver in windows safe mode and reinstalled the latest driver.
It was all going so well until I reinstalled the nVidia driver.
Halfway through installation the screen went blank and wouldn't display until I connected an HDMI monitor!
I sorted it by going into nVidia Control Panel and telling nVidia to only use the DP monitor.
Somehow, despite using the DDU cleaner nVidia must've still been loking for the previously connected HDMI monitor.

 

[hang-the-9]

I got it sorted eventualy
On cold boot the BIOS was showing but on OS load the screen would go blank until I plugged in an HDMI monitor.!
Using the DDU driver removal tool in the sticky thread I cleaned off theold driver in windows safe mode and reinstalled the latest driver.
It was all going so well until I reinstalled the nVidia driver.
Halfway through installation the screen went blank and wouldn't display until I connected an HDMI monitor!
I sorted it by going into nVidia Control Panel and telling nVidia to only use the DP monitor.
Somehow, despite using the DDU cleaner nVidia must've still been loking for the previously connected HDMI monitor.

This is why I checked to see if the port worked before Windows started, the fact that it did then stopped showed it was some driver issue.