You would need someone to write an app that could interface with the desired connection (network,bluetooth,...) and the motherbds bios and then a second app to run on your phone to control it.
No offense, but I fail to see the point of such a product. If you pc needs the fan adjusted then you are sitting right in front of it, why waste time pulling out the phone when you can just launch the fan controller app (manufacturers or aftermarket/freeware) right on the pc?