Asus DSEB-D16/SAS - Manual (Page 46)

2-26 Chapter 2: Hardware information
5. Connect the fan cable to the
4-pin connector labeled FBD_FAN1.
4. Position top cover over the fan
base. Insert the top cover legs into
the slot on the fan base legs.
Push down carefully until the legs
are securely in place and the top
cover hooks snap in place.
Make sure the cables pass
through the notch on the fan base
as shown.
6. Repeat the previous instructions to install the other FB-DIMM fan if needed.