I'd replace the 92mm Zalman fan, but for a quieter one. It's too loud for me, hums too much even at the lowest Fanmate setting (5V). In general, I find 80-92mm fans are about the quietest. Smaller, they whine; larger they grumble (hum, other lower pitched noise). Has to do with the size of the motor / coils / mass, I think. Haven't tried any of the 92mm Panaflos, but the 92mm Silencer from PCPower&Cooling is very quiet, much better than the Zalman.
<br>A simple SPL rating or measurement really doesn't tell you about the quality of that sound -- I find some fans have less bearing noise, so even if they're running faster & blowing more air & measuring say 2 dB louder, it can sound "better" (less intrusive) than one which runs slower and thus has less airflow noise but its bearing chatter a bit.
<br>If you need more cooling, go for the big one, I guess, or you could double up on 2 quieter fans like John Coyle did <!-- BBCode Start --><A HREF="http://www.silentpcreview.com/goto.php?t=s&id=18&a=3" TARGET="_blank">here.</A><!-- BBCode End --> Generally 2 quiet fans are quieter than 1 louder fan for the same airflow.
<br>What are you trying to cool?
Mike Chin, SPCR Editor/Publisher
Support SPCR by buying your gear through this link: Amazon