How can a Perfmon "% Processor Time" counter be over 100%?
There are two counters with the same name:
Process\% Processor Time
: The sum of processor time on each processor
Processor(_Total)\% Processor Time
: The total for all processors
Your question indicates you're using the first counter, which means that its maximum value is 100% * (no of CPUs).
So if you have 4 CPUs, then the total maximum is 400%, and 80% is actually (400 * 0.8 =) 320% (and for 8 CPUs it's 640%, etc etc)