By Andrew Armstrong 
A dusty PC gets hot, a hot PC throttles, and a throttling PC feels slow in a way that looks like a software problem. Cleaning it is genuinely worth doing, and there are a few ways to do real damage in the process, mostly by doing something that seems obviously sensible.
Quick Facts
- Never let fans spin freely under compressed air. Hold the blades. A spun fan generates current back into the header.
- Household vacuums generate static. Use compressed air, or an anti-static blower designed for electronics.
- Thermal paste on a normal desktop lasts five years or more. Replacing it annually is unnecessary.
- Take temperature readings before and after, or you won’t know whether it worked.
- Dust filters are the difference between doing this yearly and doing it monthly.
What you need
- Compressed air. Canned, or better, an electric blower (cheaper over time, no propellant).
- Soft brush. A clean paintbrush is fine for loosening stubborn dust.
- Microfibre cloth for surfaces and glass panels.
- Isopropyl alcohol 90%+ and lint-free wipes, only if you’re redoing thermal paste.
- Thermal paste, only if you’re actually removing the cooler.
Not needed: a vacuum cleaner. The airflow through a plastic nozzle builds a static charge, and static is one of the few things that can genuinely kill components outright.
Before you start
Quick Steps
- Record your temperatures. Run something demanding for ten minutes and note idle and load figures. HWiNFO or Core Temp will show you.
- Shut down fully and unplug from the wall.
- Hold the power button for 15 seconds with the power off to discharge residual current.
- Move it somewhere you don’t mind making dusty. Outdoors or a garage is ideal.
- Touch bare metal on the case periodically, or wear a strap if you have one.
That first step is the one people skip, and it’s what turns “I cleaned my PC” into “cleaning my PC dropped load temperatures by 14 degrees”.
The clean itself
Quick Steps
- Open the side panel. Remove dust filters and wash them separately. dry completely before refitting.
- Hold each fan’s blades still, then blow dust out. This applies to case fans, the CPU cooler and the GPU.
- Blow through the CPU heatsink fins along the fin direction, not across them.
- Do the GPU carefully. Hold its fans too, and don’t force air into the bearing.
- Brush stubborn dust from filters and grilles, then blow again.
- Wipe surfaces and glass with a barely damp microfibre cloth.
- Check every cable is still seated before closing up.
Short bursts rather than continuous blasting, and keep canned air upright. Tilting it releases liquid propellant, which is cold enough to cause thermal shock on a component.
Thermal paste. When it actually needs doing
Thermal paste gets replaced far more often than it needs to be. On a normal desktop, quality paste lasts five years or more. Replace it when:
- Temperatures are high after a thorough dust clean.
- You’ve removed the cooler for any reason, always reapply, never reuse a disturbed thermal joint.
- The machine is genuinely old and has never had it done.
- You’re seeing thermal throttling under load with a clean, well-mounted cooler.
If you are doing it: remove the cooler, clean both surfaces with isopropyl and a lint-free wipe until they’re mirror-clean, apply a pea-sized amount to the centre of the CPU, and refit. Mounting pressure spreads it. Spreading it manually tends to introduce air gaps.
On a laptop, this is a considerably bigger job and often involves removing the entire mainboard. Worth doing on an old machine that throttles, but read a teardown guide for your exact model first.
Did it work?
Run the same load test and compare against the figures you took beforehand.
| Component | Idle | Under load | Cause for concern |
| CPU | 30-45°C | 60-80°C | Sustained 95°C+ or throttling |
| GPU | 30-50°C | 65-83°C | Sustained 85°C+ |
| NVMe SSD | 30-50°C | up to ~70°C | Throttling warnings in software |
A good clean on a genuinely dusty machine typically takes 5-15°C off load temperatures. If it didn’t move at all, the problem probably isn’t dust. Look at cooler mounting, case airflow, or a fan that’s stopped spinning.
Keeping it that way
- Fit dust filters if the case doesn’t have them, and clean them monthly. Far easier than a full strip-down.
- Positive pressure helps. Slightly more intake than exhaust means air enters through filters rather than every gap.
- Get it off the floor, especially carpet. Floor-level intakes pull in dust and hair constantly.
- Pets and smoking multiply the frequency. Every three months rather than annually.
Glossary
| Term | What it means |
| Thermal throttling | A component reducing its own speed to stay within temperature limits. |
| Thermal paste | Compound filling microscopic gaps between CPU and cooler to transfer heat. |
| Positive pressure | More intake than exhaust airflow, so air enters through filters rather than gaps. |
| Isopropyl alcohol | The solvent used to clean thermal surfaces. Evaporates without residue. |
| Dust filter | A mesh screen over intakes catching dust before it enters. |
| Fan header | The motherboard connector a fan plugs into. Vulnerable to current from a spun fan. |
Frequently asked questions
Can I use a vacuum cleaner to clean my PC?
Not a household one. The airflow over plastic generates static that can damage components. Compressed air or an anti-static electronics blower is the safe option.
How often should I clean my PC?
Once a year for a typical machine on a desk. Every three months if it sits on carpet, or if there are pets or smokers in the house. Dust filters, cleaned monthly, make a big difference either way.
Do I need to replace thermal paste when I clean it?
No. Only if you remove the cooler, or if temperatures are still high after cleaning. Quality paste lasts five years or more in a normal desktop.
Why hold the fans still?
A spinning fan acts as a small generator, feeding current back into the motherboard header. It can damage the header or the fan controller. Hold the blades with a finger while blowing.
My temperatures didn’t improve after cleaning. What now?
Then dust wasn’t the problem. Check the cooler is properly seated, that all fans are actually spinning, and that case airflow isn’t obstructed. On an older machine, dried thermal paste is the next thing to look at.
Gear We Recommend
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