x570 tomahawk mobo no bios video output.

[pzr vr6]

i have an x570 tomahawk mobo and i cant get into the bios. just got a black screen, i THINK its going into the bios i just get no video output, i get no flash screen at startup either, the 1st thing i see on a normal boot is windows. im sure iv had this issue before with it and cant remember how i sorted it