I found you can have further control by going into Power Options and changing the minimum and maximum processor percentages.
You can pretty much change the clock speed down to whatever you want and make the fan even quieter, at the expense of processing power of course, but even setting it to 80 or 90% seems to make a difference to the fan noise.
I initially hated the box for the fan noise but now I've discovered how to tweak I actually really like it as I can tune it pretty much to how I want it to be.