Most box fans are rated for a lot more than 1000 cfm - even the cheap Lasko ones like Walmart sells.
Down side - don't try to push a lot of air with them if you have any restrictiveness in your airflow path, their airflow goes down a TON in that sort of situation.
that is a cheap lasko box fan as the push fan
http://www.laskoproducts.com/wp-content/uploads/B20570WeatherShieldBoxFanwithThermostat.pdfif you have any link of any kind that shows how much air they push please provide it.
I put 1000cfm to be conservative as I can not find a cfm spec anyplace at all.
the 1600 cfm gable fan was 120 usd vs 30 usd for the lasko and the cfm was clearly marked.
and the box fan is not high velocity so with lots of restriction it loses force.
I went back to home depot and found this one from lasko.
it read 2500 cfm max:
PRODUCT OVERVIEW Model # 3733 Internet # 100405665 Store SKU # 399582
The LASKO 20 in. 3-Speed Box Fan combines the cooling power of 3 fan speeds with
the wide-area air flow of 2,500 CFM air circulation and a 20 in. fan diameter, all in a compact, lightweight, energy-efficient design. The 6 ft. cord and slip-resistant feet allow flexible placement without fan slippage and the built-in carry handle makes it easy to transport the fan between rooms. The plastic material provides reliable strength and durability.
3 speeds make it easy to select a customized airflow level
Circulates up to 2,500 CFM for ample cooling power
Plastic housing provides durability and strength for extended use
Energy-efficient design helps conserve power
6 ft. cord allows flexible placement away from an outlet
Slip-resistant feet help prevent fan sliding for improved safety during use
Compact, lightweight design for convenience
Built-in carry handle makes it easy to transport the fan between rooms
Standalone design
ETL safety listed
I bolded the wide area flow that means lower velocity and lack of penetration ability as noted by QuintLeo
So the point is the two fans I am using will cool 6500 watts of gear or 5-6 s-7's
so 50 s-7s or s-9's means more fan power.
maybe 5 gable fans like this:
http://www.homedepot.com/p/QuietCool-Professional-3013-CFM-Power-Gable-Mount-Attic-Fan-AFG-PRO-3-0/206047381these 5 = 15000 cfm on the pull side
and maybe 10 of these on the push side.
http://www.homedepot.com/p/Lasko-20-in-3-Speed-Box-Fan-3733/100405665set the gear on racks like these
http://www.homedepot.com/p/HDX-5-Shelf-36-in-W-x-16-in-L-x-72-in-H-Storage-Unit-21656PS-YOW/100656305with the box fans pushing at them. and the gable fans pulling air out of the building