To be honest it is unlikely that a Bios update will make any difference to the fan. after having a look at the manual it does not look like it is possible to remove the fan easily to either clean it or replace. My old Toshiba was just a matter of removing 4 screws to access the fan bay.
I do not know if there is a setting within the bios to control fan speed.Here's a bit more reading. http://www.ehow.com/how4547829adjust-laptop-fan-speed.html