I am having this exact same problem, but the thread was closed and so I can't ask the OP for the fix: Same case and motherboard... 

I have a X670E Hero motherboard and I would like to add a Thunderbolt 4 KVM so that I can switch between a Mac and my Windows PC. Currently, I have it setup with a KVM that runs a USB 3 cable from the motherboard to KVM for peripherals and a DisplayP...

I have an X670E Crosshair Hero motherboard. I used to get the option to enter the BIOS on cold boot, but lately that option does not exist, it just goes straight to Windows. I can restart from Windows and have the option, but not from a cold boot. I ...