Your mobo should have a cool and quiet type throttling function yes,
lowering the refclock and multi when its not needed,
and putting it back up when it is needed
unless you disable it in bios ofc.
my current pc has that motherboard and Phenom II X4 955, and I use K10STAT and everything is ok
I was asking because I'll probably buy a FX-8120 with a new mobo, and wanted to know how it would behave with manual voltage and ratio settings