Acer B277 monitor shows "Input not supported" on boot, also can't display BIOS

Hi everyone, recently I built a new PC and wanted to use my Acer B277 monitor with it. Everything is fine except that on boot, instead of showing the motherboard manufacturer's logo, the monitor shows a floating box displaying "Input not supported". After a few seconds, when I would presume Windows has been loaded, the monitor shows the Windows log-in screen. I have also noticed that the BIOS is unable to be displayed; it showed "Input not supported" (until I pressed Esc and Enter keys and exited from the BIOS).

My PC:

Motherboard: MSI Pro Z 690-A Wifi (MS-7D25)
CPU: Intel i5-12600k
GPU: MSI Radeon RX 6600x MECH 2X 8G OC
HDMI to HDMI cable for the monitor

What I have tried:

Connecting my PC to my TV: everything worked perfectly. Clearly shows MSI logo on boot, can easily access BIOS. I don't think any parts in my PC or the HDMI cable are faulty or damaged, and rather, there is some resolution incompatibility between the PC and the monitor (?)
Going into BIOS (with the TV) and changing from UEFI to CSM: no effect
Using DDU in safe mode, then reinstalling GPU drivers: no effect
Installing the newest monitor drivers: no effect
Going into Windows display settings and changing resolution and refresh rate: no effect
Going into AMD Software and enabling GPU scaling: no effect

I'm thinking of buying a new monitor at this point but I really hope I can fix this on my own. Please help me solve this problem!

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billsey

It's an issue with the GPU. It doesn't scale from the lower resolutions to anything the monitor supports, so 640x480 or 800x600 resolutions and passed directly to the monitor, and those are outside the resolutions supported. Check to see if there's any sort of option to set in the GPU software to rescale to something like the native resolution of the monitor. It needs to rescale at initialization, and not wait for Windows to load the Windows driver...

kailinho

billsey said:

It's an issue with the GPU. It doesn't scale from the lower resolutions to anything the monitor supports, so 640x480 or 800x600 resolutions and passed directly to the monitor, and those are outside the resolutions supported. Check to see if there's any sort of option to set in the GPU software to rescale to something like the native resolution of the monitor. It needs to rescale at initialization, and not wait for Windows to load the Windows driver...

Hi billsey, thank you for the suggestion. The closest thing I could find to what you described in the AMD software was something called "GPU scaling", as shown here. I've tried all three "Scaling modes"—preserve aspect ratio, full panel, and center—but to no avail.

Image: https://us.v-cdn.net/6029997/uploads/editor/b3/icdg0zcpfw1q.png

I've also tried bcdedit.exe -set {globalsettings} highestmode on in hopes that this would make the boot screen use the highest resolution possible, but that didn't work either.

The lowest resolution my monitor supports is 800x600 so I'm assuming that the boot screen and BIOS are both in unsupported 640x480. Would I have no choice but to buy a new monitor which supports this resolution? I can't seem to find a way for telling the GPU to rescale.

billsey

Hmm, try asking in the GPU vendor's support forum, it doesn't look like that option is getting saved to the UEFI BIOS, so it's not initialized to that during boot. The card has it initial settings configured as part of the UFI load after the BIOS POST has completed.

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