Another great review TTL style.
You got a bit confused in the video Tom. Slow brain to mouth connection?
IR3555M are smart power stages. They integrate both high, and low side mosfets with additional sensing, and protection circuits into one package. They are those chips above inductors (chokes) at the front. SMDs at the back are capacitors for ironing out the current. Either aluminium polymer, or tantalum.
Pretty much all VRM controllers on motherboards have 8 PWM signals. ASUS uses 8 PWM signals with 2 power stages for each signal. And in that case 8 PWM signals interleaving. MSI uses doublers for each PWM signal so in the end there are 16 PWM signals interleaving (one for each power stage). Both VRMs spread the load over 16 power stages for better efficiency.