Laptop overheating and slowing down? It is not old, it is hot

Here is the pattern. The laptop boots quickly, works normally, and then somewhere around the twenty minute mark it turns to treacle. The fan is loud. The base is hot. That is a laptop overheating, and it is one of the cheapest faults we fix.

Why heat makes a laptop slow

Processors protect themselves. When the temperature passes a safe limit, the chip deliberately reduces its own speed so it stops producing heat. Engineers call this thermal throttling.

So the slowdown is not damage. It is a safety response. Consequently, remove the heat and the speed comes straight back.

What actually causes it

Three things, usually together. First, dust. Air is pulled through the machine every day, and over two or three years the heatsink fins pack solid with felt-like dust that no amount of canned air will shift.

Second, thermal paste. Over time the paste between the processor and the heatsink dries out and stops conducting heat. Around the four year mark, most laptops need it renewed.

Third, the fan itself. Bearings wear, so it spins slower than it reports and airflow drops. Often you can hear this as a rattle or a whine.

Check it yourself first

Install a free temperature monitor and watch the processor while you work. Idle should sit well under 60 degrees. Under load, anything sustained above 90 means the cooling is not coping.

Also look at where the air goes. If the vents are on the underside and you use the laptop on a bed, a sofa or your lap, you are blocking them completely. A hard surface alone can drop temperatures noticeably.

Intel publishes the safe operating range for its processors on its support pages, and the numbers are worth knowing before you panic.

What a proper clean involves

A real thermal service means opening the machine, removing the heatsink assembly, clearing the fins physically, cleaning off the old paste and applying fresh. Then the fan is tested under load.

This is the cheapest visit we do, and it is the one that most often saves a laptop somebody had already decided to replace. See our cooling and performance service for what is included.

When it is not heat

If temperatures are fine and the machine is still slow, look at the drive instead. A failing disk produces exactly the same symptoms. Our guide on hard drive repair covers how to test that properly.