To work Fan Xpert needs Q-Fan to be enabled in the BIOS. Fan Xpert once working should offer you a choice of profiles, of which Silent could be the best option. As you can already see there is a fan calibration facility which should establish the lowest speeds at which the CPU fan can run.
I have Q-Fan enabled in BIOS. When I start AI Suite, there is nothing to open up (no Fan Xpert). But it does seem to be stuck in the performance setting, I can't change anything and all options are greyed out.
Also, I tried just plugging the stock cpu fan, and that too seems to spin too fast. I'm thinking something is wrong with my motherboard of bios.