Originally Posted by Bobicon
How do they measure combined CFM then?
Also I am guessing two of these fans will be better than the stock fans Hyper N520 fans.
They measure the output. You can't compute it. For one thing, the resistance of the fin stack will differ between heatsinks. So, to know what your output will be you must measure, and most of us don't have the equipment for that.
I don't really care about the cfm per se, just what the fans actually do. This is why I measure the effects of fans; i. e. - core temps in a standard heatsink setup.
But for a rule of thumb, I figure that if I have a single fan pushing 50cfm, in a single-fan setup the airflow will be less than 50cfm. If I put on a second 50cfm as pull fan, I expect the total output to approach 50cfm. I don't expect more.