Is there a BIOS setting for the fan or a Sony plug in to allow regulation of the speed? My stock Intel CPU fan runs at variable speeds based on load (my guess is more on CPU temp than actual load). Maybe your CPU has poor ventilation? Could there be a lot of dust inside or blocking a vent?
When I enter the BIOS, there are two settings for the fans. There is no option to change them.
I was told Sony does not allow access to those setting in their computer. A big reason I regret buying a Sony computer.
I too the computer back to Sony and they replaced the fan. Nothing has changed.