So I purchased a new 27" QHD monitor (2560x1440) from Dell, and later on discovered that it has USB-C connector, and 2 HDMI inputs (sadly, no Display Port). The Radeon 5600XT has Display port and HDMI. The only cables I have are DP->DP, USB-C → USB-C, and DP->HDMI (1.4). The only combination that works is DP->HDMI. So lets test it:
So under Haiku and VESA drivers, the monitor comes up nicely as 2560x1440. Yay Haiku, works like a charm. I can even set refresh rates to 75Hz. All is good with VESA driver in Haiku.
Under both Windows 11 and Linux Mint, the monitor is restricted to 2048x1080. Obviously the AMD driver doesn’t like something with the HDMI cable (rated 1.4). So it drops the resolution to this weird resolution.
So I’m fuming right now that the big boys cannot get the driver right for this combination, yet with VESA it obviously works. And I need to order another cable combination (probably DisplayPort out to USB-C in). Rage mode ON.