By default the fans run at relatively high speed in comparison to desktop systems. If you are running one of these servers in an office environment then you may want it to run a little quieter. What follows are the impitool command to bring the Dell T630 (should work on other Dell Servers) fans down to 20%:
ipmitool -I lanplus -H 192.168.0.152 -U root -P calvin raw 0x30 0xce 0x00 0x16 0x05 0x00 0x00 0x00 0x05 0x00 0x01 0x00 0x00
ipmitool -I lanplus -H 192.168.0.152 -U root -P calvin raw 0x30 0x30 0x01 0x00
ipmitool -I lanplus -H 192.168.0.152 -U root -P calvin raw 0x30 0x30 0x02 0xff 0x14