SIIG Transport GX21 B5350 - Manual (Page 44)

3.7 Replacing the cooling fans
38 Chapter 3: Replacing installed components
6. Remove the four screws securing each fan to the fan
bracket to remove them from the fan bracket.
Note:
The Transport GX21 (B5350) uses
two different types of cooling fans which
operate at different speeds. The fan installed
nearest the power supply has a peak speed
of 15,000 rpm. The other 4 fans have a peak
speed of 15,500 rpm. The fan nearest the
power supply should be connected to the
speed-controllable pin header (CPU1_FAN)
on the mother board.