You can have quiet good cooling in an air cooled AMD system.
The 80mm fan trick does work wonders, and there really isn't any more of a dead spot, as most centers of 80mm fans are about the same size as the 38cfm Deltas...and yuo also get more blade size.
I currently have an FOP38 with a low CFM 80mm, and it keeps my tbrid900 at 48C at 1017.
However, I just ordered a week ago the new GlobalWin WBK38...it has the same fan clip style that will allow for the 80mm fan to be attached. Also, I got...I believe it was a 40+ cfm 80mm fan for it...that should keep things nice and cool, yet be pretty quiet.
Check out
www.heatsinkfactory.com. They put dBa ratings with all their fans, as well as CFM ratings so you can find your balance.
Currently the WBK is 25 bucks, add an 8-10 dollar fan, do some lapping, get some Artic Silver grease, and you'll be cool and quiet.
Also, the less efficient FOP series is about 19 now...but I wouldn't bother trying to save the 6 bucks and get teh wbk...
Hope you keep your cpu cool and quiet.
Mike