Looking for a competent, quiet air cooler for either a 3570K or 3770K CPU paired with an ASUS P8Z77 mobo that has Fan Xpert 2. Still need to research clearance with RAM and nearby mobo components as well.

Budget is anything under $110, which would need to include the swapping out of any fans needed to make a cooler quieter.

Would run either CPU at stock speeds initially, but may try a mild OC down the road if temps can be kept in check. Longevity is as important as speed, as this will be my main home computer for the next 3-4 years. Currently running an E6750 Core 2 Duo system, so you can see how often I build a new system.

I don't know for sure, but I think both stock fans on the NH-D14 (NF-P14 and NF-P12) are 3-pin and not 4-pin PWM - so not controllable via Fan Xpert 2, right? If that's the case and both fans would run at 100% all the time, should I should plan to swap out the fans for PWM fans?

With the Megahalems Rev C, I would buy 2 PWM fans to plug into motherboard PWM fan headers. I believe the ASUS P8Z77 mobos with Fan Xpert 2 have two CPU PWM fan headers, right?

Sorry if these are elementary questions. Thanks in advance for the education!

J

Take a look at the recommended heatsink list.
For lowest noise you'll want a high performance heatsink with wide fin spacing and a single low RPM PWM fan, will run with FanExpert(2+) on the lowest setting anyway.
My recommendations, in order:
Thermalright HR-02 Macho. Great heatsink, good fan, have the HR02 (non-Macho) myself.
Scythe Ninja (2/3) Good for low RPMs. Scythe Mugen 3 is not far behind
Prolimatech Megahalems MAYBE little better at 500RPM than HR02, but much more expensive.
Noctua NH-D14 dual tower MAYBE little better at 500RPM than HR02, with two good fans, extremely expensive. Very wide, too you might run into problems with RAM heatspreader (Solution: buy low profile RAM).

In short HR02, Ninja or Mugen, the rest might bring a very minor improvement. Optimizing your case and case's airflow will have a bigger impact, with the money saved going from Noctua to HR02, get a better case like Fractal Design R4 (not R3) or Antec 18X.

Thermalright SIlver Arrow. Either the old SB or the newer SB-E (but not the SB-E Extreme). Just as if not slightly better thermal performance as the Noctua NH-D14, but with notably quieter fans.

Thermalright Venomous X if you have space issues. Replace the fan.