the point is that its 100% of f.i. 80% of the max frequency
if you have a 10GhZ core and you set the max usage to 80% it will still use 100% but just 100% of the 80% so it runs just @ 8GhZ -> less power consumption, colder CPU (which makes it live longer)
if youre not usin other GhZ-hungry applications either way (night while sleepin, just browsin..) you can just set it to ~80% for your real PC (not in the VMs)
if you have a 10GhZ core and you set the max usage to 80% it will still use 100% but just 100% of the 80% so it runs just @ 8GhZ -> less power consumption, colder CPU (which makes it live longer)
if youre not usin other GhZ-hungry applications either way (night while sleepin, just browsin..) you can just set it to ~80% for your real PC (not in the VMs)