I can finally drop the fan speed below 1000rpm and still have peace & quiet.
Coolant is 525ml distilled water and 75ml antifreeze. (72:1 if i've got my maths right)
Proof that my mathematical ability is somewhat poor. I really should double check myself before i start typing this stuff. (just redone my calculations and it comes out to 7:1 like you said, can't even remember what I did to get 72:1)
air cooling will have to do for me atm.

