The way to solve it is to sell it and replace it with a Vega 7.
Really, I used to have the standard version, after that I got the All-Aluminium limited edition. The short version of the story,.. the default duct cooler is junk, no matter how you spin it. It will never be quiet and it will never cool. Sell you junker as fast as possible. The three fan Vega is so much better, you wouldn't believe it. But then again, there is the 5700 now if you are into OPEN Core....