I have SuperMicro CSE-815 server with X9DRI-LN4f Systemboard. I've been looking around for a utility that will turn down the fans. SD5 seems to do a great job of monitoring, but it does not appear to let you reduce the Max speed.
You can control FAN speeds via IPMI WebGUI or use ipmicfg command prompt.
(ex. ipmicfg -fan 0 -> this command reduces the fan speed to Standard)
0: Standard
1: Full
2: Optimal