I have a Noctua NH-C14 in an Antec Fusion case with only the lower fan installed (since there's around 16mm clearance above the heat sink). I'm actually satisfied with the cooling (much better than with a Ninja Mini I had previously). It could be quieter, but the case is constraining my cooling options - and when I got the case 10 years ago, I really needed a HTPC case...
I was thinkin about installing a 140mm slim fan on top of it - just for giggles . I've found the following slim 140mm fans (all, except ThermalTake, are PWM):
- Prolimatech Ultra Sleek Vortex 14
- Cryorig XT140
- Thermalright TY-14013 - also comes in red
- Thermaltake Luna 14 Slim LED Blue (also available with white and red leds)
- Raijintek Aeolus α (in Red, Black or B&W)
- Silverstone FW141
There is only barely enough room above the NH-C14 (and case ceiling) for a 13-15mm fan, and hence I don't think it will actually improve things much. But since I like to tinker with things, just for the heck of it I'm consider getting one. Will it resonate with so little space? Will the in 1-2mm clearance cause atrocious turbulence, making the fan sing? Or, will it work without issues despite nearly non-existent clearance - what are the limits for operating a fan?
Of course there's a plethora of 120mm slim fans that I could also try, but since in this case the installation location is not challenged in width, I might go for a 140mm fan... (however, since there is a shallow "pit" on the NH-C14, a 120mm fan might just have enough clearance for airflow, that a 140mm fan does not have - if I manage to mount it in a sensible way).
Also, as my needs and goals for my PC build have changed, I might part with the Antec Fusion some time in the future, and change to a more conventional desktop case - in which case it doesn't hurt to have some extra fans to play around with.
Cheers!
P.s. As a sidenote for any Antec Fusion / NSK2400 or similar users: my preiliminary findings indicate that the NH-C14 is much more efficient than the Ninja Mini I had installed previously. It is a perfect fit into this case - practically all the space that can be is filled with heatsink . It fills so much that depending on the MB layout one might run into problems; on my Asus Maximus VII Gene, there's about 1mm clearance to the PCIe slot from a fan clip (if the NH-C14 is installed so that fins are pointing to the exhaust fans).
EDIT:Added Raijintek's Aeolus α, Silverstone FW141