Is it true that NF-A15 a 140mm fan will fit 120 mm cases and if so how? I want to use 2 of them in push pull on my radiator.
The NF-A15 is a 150mm fan, that uses 140mm mounting holes. No, you can't use it on your 120mm radiator, but, the Noctua NF-F12 is perfect for what you want to use them for.
I actually just found this http://www.youtube.com/watch?v=y5WzAgRcFGo.
Theres a video where Linus demonstrates it on a 120 mm cpu fan. Its a 140mm fan with 120 mm holes.
Also on there website http://www.noctua.at/main.php?show=140mm_frame_types
The NF-A15’s standard 120mm mounting holes (105mm spacing) also make it an ideal performance upgrade for 120mm case or CPU fans.
Oh, must be thinking of a different Noctua; there are so many damn fans. Sure, if there is clearance in your case for the extra fan, as long as the mounting holes are 120mm, you'll be fine.