I just got these fans today, they are very quiet, but they also dont spin up that much... I'm not so sure it really has what I'd call adequate cooling in it for that PSU.If anyone is chasing fans for their PSU, these are cheap with worldwide shipping.
They aren't 40x40x40 they're 40x40x10 but they should work fine. I just ordered some, and they are WAY cheaper that most of the alternatives. I plan on using a bit of hot glue to hold them in place.
Most of the other 40x40x* fans were quite expensive.
It doesn't bother me because i only use it in short bursts. 4.5cfm airflow fans are are probably not enough!
The Noctua's are 5.5cfm... only a little better but still better... also more $$ as well!