Editing Corsair Obsidian 900D (section)

==Cooling==

When it comes to silent cooling, Noctua CPU coolers are the best.  So, they were the natural choice this build. In this case, [http://www.quietpc.com/nh-udxi4 Noctua NH-U12DX i4 coolers] were used.  NH-U9DX i4 could also have been a good choice but it’s better to have bigger fans so that one fan per CPU is enough.  There is an option to add an additional one if required.  Don’t forget to factor in the height of the fans once mounted as it’s a commonly-made mistake and the casing doesn’t close, once mounted on top of the CPU. 

Another consideration when buying cooling fans is RAM slot access but fortunately, the motherboard used is designed well enough to have RAM slots a bit further away. So, even with the lower NH-U9DX i4, they remain accessible.