stacking fans?

[Titan]

I have 2 Athlon XP 1800+ cpus in my case with nice evercool coolers you can check out here.

http://www.2fastcpu.com/cud-725/page1.html

supposedly the rpm is anywhere from 3800 to 4200 and cfm anywhere from 38 to 42. My system mmonitor reads 4800 rpms. The rated noise is only 30-32 dba, but of course, i can't verify that. My observation is that these are some nice high stock ratings for just a 70mm fan (albiet, a thick one).

I am redoing the cooling in my case, and have some extra panaflo 80mm fans coming in. (27cfm, 21 dba) along with a couple 70 to 80mm adaptors. Assuming I can fit the 80mms in my case, i'm not sure if it's wise, because they move less air (despite being a bigger fan).

So my question is: would it work if i stacked the adaptor on top of the 70mm fan, and had an 80mm panaflo above it? Would the cooling increase noticably?

 

[pelikan]

Stacking fans doesn't work very well. It increases noise without increasing air flow.
In the case you are mentioning, the panaflo would not be giving the 70mm fan underneath it enough air.
You could try just the panaflo with the adapter and see if your system still runs stable. It probably would if your case is well ventilated. I only use panaflos, including on my cpu heatsink.

 

[0roo0roo]

stacked fans do not increase airflow in freeair. however.. single fans have very little power against resistence. stacking fans increases power against resistence, lowering loss of cfm due to said resistence. it does not increase max airflow possible, stacked fans push only as much max air as the lowest cfm fan.