I don't know, then. The monitor's manual describes an "aspect ratio" setting with "16:9", "auto resize", "4:3", and "1:1" options, which implies the monitor do

I don't know, then. The monitor's manual describes an "aspect ratio" setting with "16:9", "auto resize", "4:3", and "1:1" options, which implies the monitor does have a scaler built-in. It sounds like they used the "1:1" setting or did something wacky with the GPU's driver such that it was centering a lower resolution screen image on native resolution output.