Here Comes the Dust :For cases without filter as most of them don't, you are better off; because you don't see it coming :-)
Well, not all filters perform the same -
Below you can see the foam filter from Lian-Li stock, after three months of use. There is not much dust trapped.
Some dusts stick on the metal frame instead.
Here is an aluminum screen (acting as filter), use in the same 3 months time and sat a few feet from the Lian-Li.
If you see more "dust" on the alum filter, you are correct. The dust is trapped on the filter instead of getting inside the case and stick on the components. The photo above is from a Cheapo X-Dreamer which came without filter. I use regular alum window screen readily available at your local hardware store to filter the dust.
In case you wonder about those favorite side window fan case.
Click to enlarge
The alum screen traps dust well; the left photo was taken after two weeks of use. The right photo is after a few second of using a little vacuum. Bear in mind, I did not install a fan there, just a hole so that the negative pressure generated by the exhaust takes care of the cooler air sucking into the case.
All air borne particles have a positive ion charge , not that I believe in the negative ion generator benefit, mind you. Dust being sucked in by the fan will be attracted by the negatively charged ground metal case. Hence, grounded metal filter will "attract" or "trap" more dust. Conversely, grounded metal filter may have less effect on neutrally charged dust particles. Nevertheless, a mesh wire like this will have little or no negative impact on air flow restriction.
In short, I found the left over roll of alum window screen I purchased to fix the patio screen door 10 years ago has turned into hell a lot of fan filters.
Next, we will take a look at how to turn a budget case with restrictive front intake or no intake at all into something that we could count on. ->