Have been trying to sort this problem out for a while - thanks a lot for reading and hope someone can help
MOBO: ASUS ROG x570-E
Memory - G Skill ddr 4 4000 128gb (32gb x 4)
video card - AMD Radeon 6900 XT
ssd - samsung 980 pro 2tb
hdd - iron wolf pro 4tb
psu - 850w evga
So this is a brand new build and I am used to nvidia usually, but decided to give AMD Radeon a try for this build as 3090 / 3080 are so hard to find. and my old tower / card had a 1080 TI, with no issue detecting all monitors @ 4K resolution (3840x2160). At first, I had trouble detecting the RAM with this mobo @ 4000 mhz, but was able to adjust the mhz to 3600, seems to be working fine now. When I booted windows, all monitors show at 2560x1440, even my ASUS ROG p279Q which is 144hz and a newer monitor. The other monitors are BENQ monitors that are also 4k, showing at 2560x1440. I tried to boot up with only the ROG monitor connected, but it still displays only 2560x1440. I tried reinstalling AMD drivers, updating windows, reflashing bios to latest version on mobo, all with no help. Really don't know where to turn here. I could try to install windows again, but feel that probably won't help - I feel this is a card issue and am close to just replacing this card with a 3090 I could find anywhere (likely for double price.) But I know that the 3090 will work out of the box for these monitors, and it will be very costly to find new monitors for my setup since I already have four that are 4K.
Thanks again guys for reading, and looking forward to any suggestions! Best, Johnny
My monitor is PG279Q - asus Rog monitor. I reinstalled windows with only this monitor plugged in via DisplayPort. Still showed as 2560x1440 max resolution. Updated mobo + graphics card afterwards, same result.