I've read somewhere that for side fans specifically, the certain grill structure for that side fan can contribute to bad noises, in my case, a humming noise
For example, i have 2 side case fans. Both are intaking. They make loud humming noises.
If i take them out of their place, (out of the fan grill, unscrew the fans from the case, ect.), they still make a slight humming noise though no where NEAR the level they hum when they act as a side intake.
I also notice that they make no humming noses whatsoever when either or both of the side fans act as exhaust (instead of the humming intake fans)
Given the above context, will replacing my side fan intakes with other side fan intakes eliminate the humming noise? Or are side case fans destined to hum?
What contributes to the fact that case fans are more likely to make a humming noise if acted as a side fan intake vs. side fan exhaust? (because, as i note, the side fans make no noise at all as an exhaust but make extremely humming noises as an intake fan).
There are multiple reasons that fans make noise, one is that they just push air noisily and this is the hardest noise to fix, two they bearings are noisy (ie sleeve vs two ball vs hydrodynamic fancy crap), and three something is in their way causing obstruction of the air thus making noise.
The last reason applies more when the obstruction is on the intake side because the fan is pulling at blocked air, and thus not slicing through what it's meant to making more turbulance and noise, when it is pushing it still makes the noise just less of it. The obstruction in your case is as you said the grills.
I find it hard to believe that when the fan is in free air it makes more noise then when it is push mode with a grill blocking the exiting air.
Anyway here's what I would suggest,
Get rid of those grills or at least replace them with higher airflow ones (the less stuff the better), cut them out if they are attached to the case.
New fans, some better bearings, controllable, good fans will make a difference in noise and heat.
If you don't want to get rid of obstructions put more fans as exhausts, as you said it makes less noise and air will still get in through vents and such.
Last but not least, do some sick ventilation modding and even had bigger and more fans (more at lower speeds to compensate for noise)