Acer Aspire T120 Problem

My mate has one of these and he has ran into a few problems...

His system seems to run for a while then just throws a BCOD up......I had a
quick look, i'm no expert but i've built my own PC's so I have a grasp of
what does what. Now, the fan on his heatsink isnt spinning so I thought that
it could be an overheating problem. We got a new fan......actually he did,
wrong size and all of that but did manage to screw an 8cm fan onto a 7 cm
heatsink (yep.....words fail me too)........now when he connect the cable to
the motherboard it doesnt always set the fan away spinning. Is there a BIOS
setting that controls the fan? Could he have switched something off.

I think the motherboard is an E22m 91TF88OU334, but I heard that Acer get
stuff from Foxxcom.

Any help would be deffinitey appreciated.

DB