This computer uses a non-standard 22-Pin Apple power supply, plus a 4-Pin 12V connector commonly found in some power supplies.

Start by disconnecting the power connectors from the motherboard, and routeing them up to the level of the power supply.

Also remove the fan connector, and route that up as well.

Remove this Screw as well.

Disconnect the Fan Connector.

Fan removal is only three screws. The one circled in yellow, one on the upper left of the frame cage (not shown), and one on the middle bottom of the frame (not shown).