you probably have cool 'n' quiet, or whatever amd calls it, enabled. i'd recomend u either disable the feature in bios and cpu-z again, or run some programs and see if it moves.
if you find thats what was going on; a lot of people will say to re-enable cnq for various reasons. im personally opposed to the feature as i find that frequently it takes longer than i want it to to adjust freq. when its needed.
edit: i just read your entire post. cool'n'quiet is absolutely the culprit