How to test a small PC in a closed cabinet

A small PC can run normally on a desk but slow down after it has been working inside a closed cabinet for a while. The cabinet may trap warm air around the computer, or the PC may simply be under heavy load for another reason.

Use the Overheating Test to check whether performance drops under load, then compare the results with the cabinet open and closed. This is a short, controlled check, not a reason to run the computer until it overheats.

Test the PC in and out of the cabinet

Check that the PC's intake and exhaust vents are not covered by objects, dust, or cabinet walls. If the computer is already shutting down, smells hot, or makes unusual noises, do not run a load test. Improve airflow first.
Let the PC sit idle for about 10 minutes, with the cabinet in its usual position. Keep the room, connected devices, and open programs the same for both comparisons.
Open the Overheating Test on the PC you want to check. Run its full-load test for the few minutes it is designed to run, and note whether the computer becomes noticeably slower or less responsive.
Let the PC cool back down before testing again. Open the cabinet door, keep the PC in the same place, and repeat the same test once. Do not change the workload or move the PC closer to a fan between runs.
Compare what you observed. Also note whether the PC's fan gets louder, whether the cabinet feels warm, and whether normal tasks feel slower after the test.

Use the same setup for both runs as closely as you can. A difference is more useful than a single result, because it helps separate the cabinet's effect from normal variation in the computer's workload.

What the result means

The PC slows down with the door closed, but not open

The cabinet is likely restricting airflow or allowing warm exhaust air to collect around the PC. It does not prove that a specific component is overheating, but it is a strong reason to improve ventilation before relying on the computer for long, demanding tasks.

The PC slows down in both tests

The cabinet may not be the only cause. Dust, a blocked vent, a failing fan, a high room temperature, or another demanding task could affect performance. Check the PC in a well-ventilated position and see whether ordinary work is still slow after it cools.

There is no obvious difference

The cabinet did not make a clear difference during this brief browser test. That does not prove the PC will stay cool during hours of gaming, rendering, or other sustained work. Some workloads produce more heat than a browser test, and the result can vary with room temperature and PC model.

The PC shuts down or becomes unstable

Stop the test. A shutdown, freeze, or sudden restart is not a normal result to keep repeating. Give the computer time to cool, move it to an open area, and check its vents and fan before trying another short test.

How to improve airflow

Clear the vents. Leave the intake and exhaust openings unobstructed. Check the PC's manual for the required clearance, since vent locations and spacing differ between models.
Give hot air a way out. If the cabinet must stay closed, use ventilation openings or a cabinet fan that moves warm air out. A fan that only stirs hot air around inside may not solve the problem.
Keep the PC out of enclosed compartments. Place it on a hard, stable surface and avoid stacking papers, fabric, or other equipment against it. Do not put the computer on a soft surface that blocks its underside vents.
Clean dust carefully. Turn off and unplug the PC before cleaning its exterior vents. Follow the manufacturer's cleaning instructions, and do not open the case if that could affect your warranty or damage parts.
Reduce sustained workload if needed. Close programs you do not need and avoid running demanding jobs in a poorly ventilated cabinet. If the PC only slows during a particular task, compare its behavior with that task stopped.
Retest after one change. Let the PC cool, then repeat the same brief comparison. Changing one thing at a time helps show whether the cabinet, clearance, or airflow change made a difference.

When the PC may need repair

If the computer still slows, freezes, or shuts down in an open area with clear vents, the problem may be inside the PC. A fan that does not spin, a fan that scrapes, or repeated shutdowns are reasons to contact the manufacturer or a repair shop. If the PC is under warranty, ask the manufacturer before opening it.

A browser test can show whether the computer's performance changes under a short load, but it cannot diagnose a damaged fan or confirm an exact internal temperature. Avoid repeated load tests if the PC is already unstable. See when repeated load tests are a bad idea for more on why.

What this test can and cannot tell you

The Overheating Test applies a brief workload and looks for signs that the PC slows as it heats up. It does not read every internal temperature sensor, check the cabinet's air circulation directly, or prove that a computer is safe for every long-running task. Treat it as a comparison, not a complete hardware diagnosis.

The test runs in your browser on the PC you are checking. Compare like with like, and stop if the computer behaves abnormally.