Settled the issue by mounting the backplate in inverted manner, and not tightening the motherboard down on the standoff in the corner of the cpu heatsink.
Power consumption figures with a Ryzen 8600G, 2x 32GB Crucial DDR5 and a Hynix Platinum P41 2TB:
Idle 10-11 W
Load: 104 W (with stress-ng...