No. The psu will just heat up to the point of either sutting down, or setting on fire (ie burning out). Pretty expensive smoke generator project if u ask me. Also u may cut your finger trying to stop the fan and then u may develop a serious infection, leading to septasemia, high fever, a stay in a local A&E and possibly a permanent stay in a six foot box if things go wrong at the hospital cos they didn't realise u were allergic to penacilin. Why would u want to stop the fan anyway?