This may not even effect GA equipment - it is being investigated but the AIX Kernel developers who are among the best UNIX kernel guru's on the planet.
The symptoms are pretty unbivous as nmon reports Scaled CPU (SCPU) as being 6 million percent busy and also the "lparstat -E" command gets confused and thinks it is not on a SPURR capable machine. Skip the -E option and watch the nsp% column (percentage from the nominal GHz speed you purchased) instead of the -E MHz numbers. Note: you have to have some power saving mode switched on or you don't see these numbers at all.
This "feature" makes no different to performance or function - just duff numbers in limited reporting tools.
I have been promised that nmon in the next release of AIX will have the SCPU (SPURR CPU) and PCPU (PURR CPU) stats as optional. They are largely pointless in most cases already (have to have power saving switched on) but because of the high numbers of physical cores and now SMT=8 on these Enterprise machines they add vast numbers of extra stats that no one wants! Fingers crossed. One massive nmon file I was send recently at 187MB (not recommended - 300 to 600 snapshots make a good graph) included 70 MB of these pointless stats :-)