Where the PC Sits Decides How Much Dust It Eats

Two identical machines, built the same week, come apart looking nothing alike after a year. One is on a desk in a room with a wooden floor. The other is on carpet beside a chair, in a house with a dog. The components did not differ; the air did.

That is the whole premise of this page. Each item below removes one specific route dust takes: the height the machine breathes at, the openings it breathes through, the pressure that decides whether it breathes through them at all, and what to do about what is already inside.

Worth being straight about the trade first: every filter costs some airflow. The honest position is that a filtered machine cleaned once a year beats an unfiltered one cleaned once a year by a wide margin, and loses to an unfiltered one cleaned every three months. If you are the second kind of person, most of this page is optional.

A note on this collection: these are chosen from published specifications and from how dust accumulates in a normal room, not from running each configuration for a year. Manufacturer airflow figures are measured with nothing in front of the fan. See how we test.

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Get it off the carpet

The first item because it is the largest single change and the one that needs no maintenance afterwards.

Carpet is both an obstruction and a supply. It blocks bottom-mounted intakes — which is where most power supplies and many front-bottom case intakes draw from — and it releases fibre continuously as people walk on it. A stand lifts the intake out of the worst few inches of air and restores the clearance the case was designed around.

The wheels matter more than they sound. A machine that can be rolled out gets cleaned; one that has to be lifted and unplugged gets cleaned when something goes wrong.

Whether the floor is acceptable at all, and what changes if it is a hard floor, is covered in should a gaming PC sit on the floor.

Magnetic filter mesh on the intakes

For the openings the case actually draws through, which on most builds are only partly filtered from the factory.

Magnetic mesh is worth the small premium over adhesive versions for one reason: you will take it off to clean it, and something you can peel away in a second gets cleaned, while something held on by tape gets left. Fit it to intakes only. Filtering an exhaust achieves nothing while the fan runs and, if the case is under positive pressure, achieves nothing at all.

Buy fewer, larger pieces than you think. Trimming one sheet to shape beats a bag of small squares that never quite line up with the mounting holes.

What that costs you in temperature, measured honestly, is in dust filters and the airflow they cost.

Covers for the openings nothing is using

The ones nobody thinks about: unused fan mounts, empty PCI slots, and the vents on a case that is switched off.

A desktop spends most of the week powered down, and while it is off there is no positive pressure and no filtering — dust simply settles in through every hole. Blanking the unused mounts closes the routes that exist for no reason, which is free of any airflow cost because nothing was moving through them.

Enough intake fans to hold positive pressure

The part that makes the filters work, and the one most builds get backwards.

If a case exhausts more than it takes in, the shortfall is made up by air pulled in through every seam, slot and gap — none of which is filtered. Add intake capacity until the case is slightly positive and the direction reverses: air leaves through the gaps, and the only way in is past a filter you chose.

Three intakes to two exhausts is a reasonable starting point on a mid-tower. Fans that daisy-chain through a single header keep the cabling manageable when you are adding several.

Getting the directions right in the first place is fan orientation, and which side is intake.

An electric duster for what is already in there

Because none of the above removes the year that is already sitting on the heatsink.

An electric duster replaces compressed air cans with a rechargeable motor: no propellant, no liquid spraying onto a board when the can gets tilted, and no consumable to run out mid-job. For anyone cleaning a machine more than twice a year it costs less than the cans it replaces.

Hold the fans still while you blow through them. Spinning a fan with an air blast drives it as a generator and can push voltage back into the header.

The routine for a house where the dust never stops arriving is keeping a PC clean in a house with pets.