What I find most astonishing (and frightening) is that the mobo designers have such a limited amount of time to design that they simply try out different components in a generic design to see it it will work.
In other words, slap in a couple of these caps here and use these MOSFETs and inductors that are mostly the same as the reference design and see if it works! The worst case scenarios might need more capacitance, but hey! it runs WinDVD, so it must be OK. Ship it!
Sounds like the easiest way to "improve" the on-board DC power supplies is to add some very low ESR filter caps and keep the MOSFETs cool. In other words, not much we can easily do.
