How to Fix Computer Overheating Caused by Blocked Heat Sink
Unplug your computer before opening the case. Wear a static wrist guard if possible, or touch the metal case before handling anything inside, to ground any static charge you may have.
Consider other options first. Overheating issues are also often caused by poor air circulation in the computer case. If you have space, adding another fan can help. Also, you should regularly open the case unplug all the cords and carefully take your computer system outside use a can of compressed air or an air compressor. A small vacuum is a good second choice but you have to be careful not to hit any internal components with it, and avoid touching the circuit boards with anything. Take your time and be very thorough with this step. Next take a cotton swab dabbed in some rubbing alcohol and go over the internal case components to get them very clean. You can go over the external case with a rag and a little bit of water. Allow your system 2 hours to dry out before turning it back on.
Remove the small CPU fan plug from the motherboard. Grasp the plastic end and pull carefully until it comes out. Don’t pull it by the wires.
Remove the CPU cooling fan. It may be held in place on the motherboard by four Phillips screws or a lock-down lever.
Release the CPU. Often it is held in place by a small lever that lifts to release the processor.
Take care not to drop the processor or pull it off if it’s stuck. Dropping the processor will likely damage it. Alternatively, it may be stuck to the heat sink by thermal paste. Try to separate them. A credit card-type card can be useful for this step, but don’t damage the CPU trying to pry them apart.
Clean out the heat sink. Blast compressed air directly on the heat sink. It only takes a few good quirts to clean a blockage. If it’s persistent, allow a few seconds before repeating.
Carefully wipe off any residual thermal paste. Use a clean cotton bud or paper towel. A little rubbing alcohol may help, but too much could cause damage.
Replace the CPU in its socket.
Apply a thin layer of thermal paste to the top of the CPU. It only takes a small amount. Too much can cause overheating problems all over again.
Replace the heat sink. Clip the clip back in. Secure the fan back on. Plug it back into the motherboard.
Tidy up the case. Make sure stray wires are secured away from fans, then put the cover back in place.
Test your computer to make sure everything works.
It’s easier to clean a heat sink on a desktop PC than it is to clean on a laptop, but you may be able to find a tutorial on how to get at the heat sink on even the most complicated laptop. Use a search engine. Even if you can’t find your model, the tutorial for a similar model can be useful.
Take photos as you go. Computer layouts vary widely and a visual record of what you took apart can really come in handy when putting it back together.
Use plastic cable ties (never metal twisty ties!) to tidy up loose wires inside your computer case. This will also help with air flow.
Motherboards vary. If you feel you need specific instructions for yours and don’t have a user’s manual, use a second computer to type the brand and model number into a search engine, then look for instructions on removing the CPU fan or heat sink. The model name/number is nearly always printed on the motherboard itself – often in the middle – and represented by a combination of letters and numbers.
Wear an anti-static wrist band when poking around inside a computer.