
Corsair Crystal 460X RGB
ATX
Corsair Crystal 460X RGB
ATX
The form factor is specified as ATX, so it should have 305mm space since ATX is standardised (as far as I know). Why does the manufacturer's website specify a maximum of 272mm for the motherboard?
Yes, that is correct. However, the 272mm stands for the width and not the height. So that would be a maximum of 305 x 272, which corresponds to an E-ATX size. However, E-ATX can have different widths.
Here are two examples (see product dimensions under specifications):
ASUS ROG STRIX X399-E GAMING (TR4, AMD X399, E-ATX)
ASUS ROG ZENITH EXTREME (TR4, AMD X399, E-ATX)