[TehCorwiz]

While this is broadly true it does ignore some interesting developments in CPU fans. Ten years ago fan sizes were smaller and blade designs less differentiated. Now, there are fans optimized for air flow for air cooled systems and fans optimized for static pressure for cooling radiators in water cooled systems. This opens up a whole bunch of questions which may obsolete these results.

Does the change and differentiation in fan blade design have implications for grill interference noise with regards to this data? Do fans that are optimized for flow versus those for pressure behave the same? Do 80mm, 120mm, and 140mm all have the same grill noise characteristics?

[whyoh]

Anecdotal, but even with the new fans, stamped out grills still perform poorly in terms of noise. They're popular because they're cheap.

I'd gladly pay $10 more for a PC case with a less noisy grill, but I can't find any that has this, not even ones that are advertised as "silent".

[rtkwe]

It's a pretty easy mod if you really want to swap to wire grills. 10 minutes with a dremel and 10 more to make it look ok again and you can have a completely open fan mount.

[fomine3]

I did it for honeycomb grill with metal scissors, and replaced to cheap metal wire ring grille. It significantly reduces noise.