Hiya

If you check the MSDN topic for @@CPU_Busy - http://msdn.microsoft.com/en-us/library/ms186925.aspx - it says explicitly that "Result is in CPU time increments, or "ticks," and is cumulative for all CPUs, so it may exceed the actual elapsed time."

I assume that this applies for multiple cores, and equally for sp_monitor, hence the inflated values which may exceed 100%.