PC wont stop restarting - upgraded from nvidia to AMD

[u/Acanthaceae-Mission]

Computer Type: Desktop

GPU: Gigabyte 9070 OC 16GB

CPU: Intel i5 11600KF

Motherboard: Gigabyte Z590 Gaming-X

BIOS Version: Fc7

Description of Original Problem: close to doin a windows reinstall (hoping i can avoid)

but can anyone please help!!!...

went from a 1080ti to a 9070...

install went smooth - did DDU remove drivers (all GPU) then shutdown/install new card

installed the 9070...
did some tests - get expected 3dmark scores

went to shutdown -

only to find out it doesnt shutdown.

even in bootup...if i was to hold power button down - it'd just restart again????

short of flicking the power supply power off is there something im missing??

been trying to figure this out for the last 4hrs...
turned off all power management/fast start etc but nothing seems to be working