However, there are a few things you can do to maximize the benefits of a push-pull setup, in my experience....
- Use the same fans, as having faster fans on one side will reduce the life of the shorter fans if there is any excess of pressure/airflow by causing the slower fan to speed up past what its motor is rated for.
- Putting a shroud on the push fans, at least, specifically something like the Phobya 120/140x7mm Shroud/Decouplers, will reduce the noise a bit as well as help with temps a bit; if you are using shrouds on both sides, I would suggest using a thicker shroud on the Push side and a thinner one on the Pull side
- If not using shrouds, then something like the new XSPC 120/240/360 rad gaskets are an excellent investment, especially at only $2-3/ea; they seal the area between the radiator and fans, preventing the loss of static pressure via air escaping between the fans and the rad
- If using the fans to intake air from outside of the case (which, if your airflow is setup properly, shouldn't make a difference), USE FILTERS! Rads seem to love dust more than just about anything else in a computer, but keep in mind that you will be ADDING to the amount of static pressure needed for the fans! I'd say that if you add a fan filter, you should up your fans' static pressure (i.e. buy more powerful fans) by ~1-1.5mmH2O to be safe.
Slow fans and thick/high-density rads are NOT the only things that benefit from push-pull setups! Just be sure to do it properly, and you'll see a 15-30% gain over a single set of fans (the exact amount varies).