Thermalright ULTRA-120 Extreme, RPM + one or two fans?

[ZzZ_Guy]

I'm getting the Thermalright ULTRA-120 Extreme CPU heat sink mainly because you pick which fan to use, and how many. It also gets good reviews for cooling and I will only be doing moderate OCing.
http://www.ncix.com/products/index.php? ... ERMALRIGHT

Looking to use either the Slip Stream or Noctua 120mm fan depending on what I can order from my local computer store (Noctua being better IMHO). The two big questions I have is what RPM and should I use just one fan or two fan for a push/pull airflow setup.

I used the two SPCR reviews.
http://www.silentpcreview.com/article69 ... tml#noctua
http://www.silentpcreview.com/article832-page1.html

Also note that I am assuming that two fans at a low RPM pushing almost as much as one of the same fan at full RPM between the two will make more noise then the single fan at full RPM, based on the noctua review I posted.

Would one fan do the job just fine or will the push/pull setup create enough extra airflow inside the heat sink that it would be worth the extra noise?

Would it even be worth it to have the push/pull fans at full/same RPM as a single one.

My current opinion is to try a single 1,200 RPM fan and add a second one if it isn't enough. If proven that the two fans are useless then replace with a 1,600/1,900 RPM version.

One last note, I'm really only concerned how quiet the fans are at idle unless the noise is so excessive I can hear it over my headphones or others can hear the PC through the walls.

[bgiddins]

If it's of any benefit, my Xigmatek HDT-S1283 has a PWM fan included that runs at about ~800RPM, I believe the performance of the S1283 is comparable to the Ultra 120. I'd go with the single 1200RPM Scythe as a starting point, unless other posters have found that this fan is not effective for the Ultra 120 - I think it has closer fin spacing that the S1283 and suffers at low fan speeds. 1200 isn't exactly "low" fan speeds though.

[mkk]

There's always the question of what you are going to cool, but moderately overclocking any new 45nm CPU with a single Slip Stream 1200 will be more than fine. By guesstimation you'll never end up running the full 1200rpm. When overclocking my own dual core E7200 to 3.8GHz at 1.36V it was more than enough to have the same type of fan running at 7V for max load runs.

[ZzZ_Guy]

Thanks for the info guys.

Btw I am OCing a AMD Phenom X4 9950 Black Edition
http://www.ncix.com/products/index.php?sku=33378