hahahaha sumbitches void a warranty for using accessories? I don't think that's gonna fly in court--oh wait this is Microsoft, they don't mind being prosecuted do they

If you really want a fan on there the simplest thing to do would be

buy a
jigsaw
soldering iron
solder
short power cord
9v battery cap
9v battery
black insulated electrical tape
shop razor
wire stripper
silver duct tape with fabric in it

open the case of the fan.  trace the power cable from the fans themselves to the power unit.  cut the wires to the power unit and take that power unit out and toss it.  No into the can.  Go pick it up. Slob.

cut a small hole into the fan case with the jigsaw.  cut the ends off the power cable, and strip the ends.  put it into the case onto the jigsaw hole.  solder the fan wires to one end of the power cable, keeping the left wires of the fans to the left wire of the power cable and the right wires to the right wire (no I don't know which is which, it doesn't matter as long as you don't cross the wires)
LET IT COOL NOOB
then wrap the soldered joints tightly with black insulated tape so no metal is exposed. exposed metal = fire

solder the little 9v battery cap to the other end of the power cable, left to left, right to right
LET IT COOL NOOB
wrap it with black insulating tape so all metal surfaces are covered

put the fan case back on so that your power cable is snugly trapped and gtg
put a 9v battery onto the cap and fasten it down with a strip of silver duct tape.  this will look like you juryrigged it yourself.  You did.

click on your power and you're gtg!!
if your friends laugh at you then stare them down and ask them if they need  Tech support to dress them too
you can throw in something about Mr. Scott and the engineer in Das Boot
if they still laugh, get new friends