Laptop overheating, loud fan and throttling — step-by-step fix

A laptop that's suddenly loud and sluggish is thermally throttling — the CPU is protecting itself by slowing down because it can't shed heat fast enough. This isn't a "get a new laptop" problem; it's nearly always a 90-minute clean and repaste away from running like new.

How to tell it's thermal

• Fan spinning flat out constantly (not just under load).
• Keyboard above the WASD area uncomfortable to touch.
• Slow and stuttery compared to how it used to run.
• Shuts down randomly under load (gaming, video rendering, Zoom).
• Battery life noticeably worse (thermal throttling runs the CPU at higher clock-per-watt for longer to try to finish tasks).

Quick check: install HWiNFO64 (Windows, free) or use iStat Menus (Mac, paid). Watch CPU package temperature under load. Over 95°C = thermally limited. 100-105°C = emergency throttling kicking in. Should be 70-85°C under sustained load on a healthy laptop.

1. Check what's running

Open Task Manager (Ctrl+Shift+Esc) or Activity Monitor. Sort by CPU.

• A single rogue app at 80%+ CPU = close that app, fan should calm down.
• Windows Defender scanning: normal for 20 min after a reboot. Let it finish.
• Chrome with 40 tabs open: Chrome is the answer to half of "laptop loud" questions.
• wudfhost.exe / WmiPrvSE.exe / svchost.exe high: Windows doing windows things, usually a faulty driver. Driver update or clean install can fix.

2. Dust (the usual suspect)

Laptop fans are small, so small amounts of dust choke them. Cats, carpets, beards and crumbs all accelerate this.

External clean (quick):

• Power off and unplug.
• Can of compressed air, straw attached.
• Spray short bursts into the exhaust vent on the side/rear. Hold the fan blade still with a wooden toothpick so the blade doesn't spin (spinning fans generate voltage and can damage the fan controller).
• Spray into the intake (usually on the bottom of the laptop).

A visible dust cloud should come out. Repeat until no more dust appears.

Internal clean (proper job):

• Unscrew the bottom case.
• Remove the fan (usually 3-4 screws + a connector).
• Brush the heatsink fins out with a soft brush.
• Vacuum or air-blast the fan itself.
• Wipe the blades with a soft cloth.

Reassemble. You'll see an immediate drop in running temp.

3. Thermal paste replacement

If dust cleaning doesn't fix it, and the laptop is 3+ years old, the thermal paste between the CPU die and the heatsink has probably dried out. The paste's job is to fill microscopic gaps between the chip and the heatsink — when it hardens and cracks, heat can't transfer.

The job:

• Bottom case off.
• Heatsink off (4-6 screws, usually).
• Old paste scraped off the CPU/GPU die and the heatsink with a plastic card, then isopropyl 99% on a lint-free cloth.
• Fresh paste applied — pea-sized drop on CPU die, same on GPU die. High-quality paste makes a real difference (Arctic MX-6, Thermal Grizzly Kryonaut, Noctua NT-H2).
• Heatsink screwed back in the right torque order (usually diagonal, small turns).
• Bottom case on, test under sustained load.

Most laptops drop 10-20°C under load after a repaste. It's like a new machine.

4. Elevate the laptop

Free fix: raise the rear of the laptop 2-3 cm. A wooden block, a couple of coins, a proper laptop stand. Most laptops intake air from the bottom; a flat surface chokes the intake. Elevation alone is worth 3-5°C on a healthy system.

Never use a laptop on a bed, sofa cushion or lap for long sessions. Soft surfaces block every vent.

5. Check the fan works

With the case open, power on and watch the fan. Does it spin up when the CPU warms? If it struggles to start, rattles, or one blade is broken, the fan needs replacing. Laptop fans cost £10-30 and take 20 minutes to swap.

A failed fan won't just make noise — it'll let the CPU cook itself. Don't ignore a dead fan to finish "one more game" — it will eventually kill the CPU permanently.

6. Firmware / BIOS update

Rare but worth checking. Some laptops ship with fan curves that are too conservative (fan stays off too long, CPU runs hot) or too aggressive (fan on at the slightest load). Manufacturers release BIOS updates that tweak these. Check your laptop manufacturer's support page for your model.

7. Undervolting (advanced, Windows)

Modern Intel and AMD CPUs can often run at lower voltages than the factory default, which reduces heat output for the same performance. Tools like Intel XTU or ThrottleStop (Intel) and Ryzen Master (AMD) let you tune this. Done carefully, it can drop sustained load temps 5-15°C with zero performance loss.

This is advanced — don't attempt unless you understand what undervolting means and are willing to spend an hour stability-testing. One wrong setting and the laptop just crashes until you reset to defaults.

When to send it in

If dust and paste don't fix it, or you don't want to crack the laptop open, we do this as a standard service. Most laptops come back running 10-20°C cooler, near-silent under normal use, and noticeably faster. Typical turnaround 3-5 working days. Free diagnosis, no-fix-no-fee, 90-day warranty.