Apple Xserve Intel (Late 2006) DIY Procedure for Power Distribution Board - Manual (Page 6)

Xserve (Late 2006) Power Distribution Board Replacement Instructions 
Fan Array
Loosen the two thumbscrews that secure the fan array to the enclosure.
Note: The thumbscrews are captive; you cannot remove them.
Lift the fan array to remove it from the Xserve.
Note: You may need to move the front panel cable slightly out of the way of the fan array
power connector during removal or replacement. Be careful not to pinch the front panel
board cable between the fan array and any other surface inside.
Note: You may encounter some resistance around the fan array power connector during removal.
If so, carefully rotate the fan array as shown to disconnect it from the power distribution board
below, and then lift the fan array out of the computer.
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