10 ways to speed up a slow PC

Reseat the CPU and GPU heatsinks

This is more applicable for the desktop, but the same basic principles apply for a laptop.

There's a small possibility that the thermal conduction between your CPU or GPU and its heatsink isn't optimal, causing things to overheat. If you want to make sure that things are fine, you're going to need some isopropyl alcohol and thermal compound.

Firstly, make sure that the heatsink is attached via mounting holes to the circuit board, rather than directly to the chip. If it appears as if there's no obvious way that the heatsink is held down on the chip, it's using thermal glue or thermal tape to form the bond. If this is the case, ignore and move on, it's unlikely these are causing you issues.

After separating the heatsink from the processor, you'll notice some goop that was last used as a thermal interface. Clean it away by applying a small amount of isopropyl alcohol to a clean cloth and rubbing it until it's gone. Apply a thin but consistent veneer of new thermal paste across the top of the chip (application can be made easier by using a scalpel or old credit card to spread the paste), then reapply the heatsink.

Credit: Matt Lauer, royalty free