-Fran-
Glorious
If lifting the power limit makes the CPU go "off-spec", then it would void the warranty as well. It'll come down to how each motherboard implements voltage delivery via VRMs power delivery. I'm also guessing VRM* efficiency becomes more important there and how they're controlling the cooling (of the VRMs).I don't think that PBO includes XMP or undervolting and lifting power limits sure does not include them.
Z boards will often do much more than just lift PL and will do things that will void your warranty like pushing an all core turbo.
I was strictly speaking about PL and nothing else.
So I don't have a straight answer for that one, other than "if the voltages go out of spec due to it, you do void the warranty".
Regards.