To expand this thread a bit, here are all the 120mm/12cm fans that are for sale on NewEgg.com in alphabetical order:
Enermax Adjustable 1500-2300RPM user adjustable $13 + $6 shipping. The fan is clear (woo woo!) and it comes with a wire grill (it's gold color!!) and it has a screw-type potentiometer for adjusting the speed -- nice. The motor hub is pretty small (so the blade area to move air is a good 85% of the 113 sq. cm), and it has 6 curved blades with radiused tips. http://www.newegg.com/app/Showimage.asp ... 012-03.JPG
Panasonic FBA12G12U1A 2750RPM 114(.7!!)CFM @ 45.5dBA with "hydro wave" bearings. $12 + $5 shipping. It has a larger motor hub than the Enermax -- my guestimate is that it has 79% blade area. It has 7 curved blades with radiused tips. http://www.newegg.com/app/Showimage.asp ... 009-02.JPG
Sunon has two 120mm fans, and both are 3100RPM monsters! One has 5 straight blades with sharp leading corners/ radiused trailing, rated at 90CFM ($10 + $6), and most of the reviews say that it is LOUD! It's hub is similar to the Panasonic. http://www.newegg.com/app/Showimage.asp ... 003-02.jpg
The other Sunon is a 38mm deep model rated at 108CFM ($12 + $6), and it also has 5 blades, but they are flared wider at the outer ends and radiused. The reviews have this one as noticeably quieter than the other Sunon. http://www.newegg.com/app/Showimage.asp ... 007-03.jpg
Thermaltake has a 2000RPM 78CFM ($10 + $6 backordered) It has 7 curved blades with sharp corners, and possibly the smallest motor hub of the group. http://www.newegg.com/app/Showimage.asp ... 113-04.JPG
Most other Thermaltake fans that I have seen reviewed have noisy bearings and lots of vibration -- this one has no user reviews.
Vantec has a 120mm Stealth that runs at 1500RPM with 53CFM ($18 + $6) It has a medium sized motor hub with 7 curved blades and smallish radii. It also appears to have it's hub supports on the exhaust side. http://www.newegg.com/app/Showimage.asp ... 614-02.JPG
That's it. One half dozen 120mm fans, and one (at least) is an obvious non-starter (the cheaper Sunon) at 12V, anyway.
From Directron http://www.directron.com/quietfans.html
there are a couple more:
Ever Cool 2000RPM, 79CFM, 30dBA, 7 very curved blades w/ sharp tips, aluminum frame and silver plastic fan, small motor hub. $12 + shipping
Panasonic L1A is rated at 30dBA and ~68CFM, no RPM listed. This is a 7 curved blade design and is otherwise similar to the faster Panasonic. $19 + shipping
Papst 4412 FGL is rated at 26dBA with 1600RPM and 55CFM. It has 5 straight blades and a medium sized motor hub. $19 + shipping
Combining these 9 with the 3 NMB's in order by increasing RPM:
Thermaltake, Ever Cool
Enermax (at full speed)
Panasonic L1A - unrated
In CFM order, lowest to highest:
The Enermax is unrated, but it might fall in the ~50CFM to ~90CFM area based on it's RPM range.
So, the Enermax looks quite interesting due to its built-in adjustabilty. The Pabst is quietest (rating) @ 12V, with the NMB #1 close behind. The Vantec and NMB #1 have potential to be very quiet but it would also move the least air (guessing at undervolting). The Thermaltake would have to have good bearings and balance (duh!) to be quiet.
As for the behemoth CFM Panasonic and Sunons, it would depend on how they behave at lower voltages. The Panasonic gets the nod for moving more air at 88% of the RPM of the Sunons.
If I get a new case that uses a 120mm fan, I'd be happy to try these out -- unless someone else wants to do it!