Oldfart wrote:

Excellent response, Paul. The only thing I would add is that in order to
flow the required air volume through the case there must be sufficient
intake area to accommodate the exhaust fan.


That's a good point, and something I had to fix on one of my computer cases.

One area I didn't address, is what happens when you use multiple fans.
The CFMs don't add together directly. Sometimes, one fan actually ends
up working against another fan (I had air blow *backwards* through
a hard drive cooler once - pretty funny). So I lack the technical details,
of how to deal with the air volume versus resistance curves and the
like. The CFM printed on the fan is not the whole story. But at least
it gets you into the right ballpark.

Paul