Written 6 Sep 2026. This is a how-to, not a product card.

When the old PC's fan is loud

A Marketplace OptiPlex or EliteDesk screams in the living room. Blow the dust, give it air, move it to a closet. Skip a water cooler this weekend.

Haven't picked a computer yet? Start with start with what you already have. Laptop under a sweater, vents blocked, hot to the touch? That is don't cook the computer. This note is the noisy desktop or office mini PC that stays on for SSH and Pi-hole, and you can hear it from the couch.

Skip until the fan is the problem

A short spin at power-on is normal. No fans and a black screen is when the old PC won't boot, not this note. A switch or UPS whining next to it is not the computer. Put your hand near the case vents. If the noise follows the computer when you move it a foot, keep reading.

What this is

Used office boxes often ship with aggressive stock fans. Years of carpet dust pack the heatsink. Sitting on soft carpet or in a closed cabinet makes the fan work harder. The fix is usually clean air and a better spot, not a new case or liquid cooler on day one.

Step 1: shut down and unplug

From the couch or the keyboard:

sudo shutdown -h now

Wait until the lights go out. Unplug the power cord. On a laptop brick, unplug wall power too. Don't open the case while it is still spinning down.

Step 2: open the side and blow the dust

Most OptiPlex and EliteDesk towers have a latch or two thumbscrews. Mini towers often slide the side panel toward the rear. Hold the case outdoors or over a trash bag. Use canned air in short bursts on the CPU heatsink, front intake, and rear exhaust. Keep the can upright so liquid propellant does not spit into the board.

Don't jam a vacuum nozzle on the fan hub. A vacuum can spin a fan past its rating and kill the bearing. If you vacuum, hold the fan blades still with a finger or a soft stick while you clean around them.

Step 3: put the panel back

These cases expect the side panel on. Running with the panel off can confuse the airflow the maker designed. Seat the panel. Latch or screw it. Plug power back in and turn it on. Listen for a minute at idle. A lot of Marketplace screamers drop a whole notch after one dust pass.

Step 4: give it air and a hard surface

Lift it off carpet and fabric. A hard shelf, a desk, or the floor with an inch of clearance at the vents is enough. Keep the front intake and rear exhaust clear. A closed cabinet with no gaps cooks the box and keeps the fan loud: don't cook the computer.

If the living room still hates the noise after cleaning, move the computer to a closet or utility shelf and reach it from the couch with SSH. The house jobs do not need to sit next to the TV.

Step 5: optional — see how warm it is from SSH

Once it is back on the network:

sensors

If that command is missing on Debian or Ubuntu:

sudo apt update && sudo apt install -y lm-sensors

sudo sensors-detect --auto

sensors

Idle CPU temps in the 30–50 °C range on a small office box are common. Sustained numbers near the maker's hot limit, or a fan that never slows after a clean and a clear shelf, mean heat is still winning. Don't chase a perfect number tonight.

Step 6: when clean air is not enough

A dying fan bearing keeps clicking or grinding after a dust pass. A replacement stock fan for that model is cheaper than a new PC. Skip water cooling, custom loops, and undervolt guides on day one.

If the box is still a hair dryer after a clean, a hard shelf, and a closet with the door cracked, a quieter mini PC is the later buy — not this weekend's homework. Quiet-versus-closet heat notes live under bedroom-shelf quiet versus closet door-shut heat. Power-bill comparison for a small new box versus a loud used 1U: a Beelink N150 vs the yearly cost of a used 1U.

What this is not

This is not a black-screen no-fan failure. That is when the old PC won't boot. It is not a laptop buried under clothes. That is don't cook the computer. It is not a reason to buy a rack, a water block, or a new case before Pi-hole works. It is not a loud PoE switch — those have their own quiet-SKU notes.

What next

Keep the computer awake if it is a laptop with the lid shut: don't let the old laptop sleep. Still setting the box up? Your first weekend. Dust out, still too loud for the room? Move it and use SSH from the couch. Later quiet-box shopping: small computers.

Optional: jot where you parked the noisy box in Lab plan — username + passkey, no email. Skip if you just want to keep reading.

Skip

• Skip a water cooler, custom loop, or new case this weekend.
• Skip vacuuming the fan hub at full power.
• Skip running the tower with the side panel off as a long-term fix.
• Skip buying a mesh kit or a new router because the PC is loud.
• Skip this if there are no fans and a black screen. Use the boot walk instead.
• Skip this if it is a laptop under fabric. Use the heat note instead.