The complete guide to upgrading your PC

Getting a little more power out of your CPU can be as easy as banishing the dust from its case

Modern processors feature thermal cut-outs that throttle back the core frequency if the CPU's temperature gets too high. In other words, if you don't maintain sufficient cooling to the processor, you won't get the full performance out of it.

The temperature at which your CPU will start easing back varies by manufacturer and model. The Core 2 Duo E4400 has a maximum temperature of 61.4C, while the E4500 operates at up to 73.3C. Online data sheets for your processor will contain this information.

How to: Optimise your cooling

1. Check current temperatures


Before taking anything out of your machine, check how hot your processor is running. CPU Hardware Monitor provides detailed temperature information for your CPU cores and motherboard, and is free.

Take a reading with nothing else running (idle) and then when another running Super Pi (under load). Then check these figures against your CPU's datasheet.

2. Remove your existing fan


Removing processor fans is easy. For Intel components, unlock the four holding pins by turning them clockwise; you're then able to pull the whole thing out.

The fans that ship with standard AMD processors are easy to remove – lift and release the holding arm and then ease the cooler out. Don't forget to unplug the fan power cable before removing it completely.

3. Wipe off the thermal grease


Before placing the cooler on your workbench, clean off the existing thermal grease using a tissue and possibly a little solvent.

You will need some more thermal grease later though, so if you don't have any new stuff , it's best to place the cooler on a piece of paper without cleaning it (so that no impurities are mixed into the existing grease). Remove the CPU and clean the grease off that too.

4. Clean the blades


Use a piece of tissue or a soft brush to clean along the line of the fan blade. Don't push too hard, though, as these can break off under pressure.

Dust tends to accumulate on the top of the fan blades, so it shouldn't be too hard to clean away. If your fan is in a housing, take it apart if needed so that you can get better access to the heatsink and the fan.

5. Add new thermal grease


Put the CPU back into its socket and apply a new layer of thermal grease to the top of the processor.

Remember, your aim is to have a very fine layer to fill in any gaps between the CPU and heatsink, not to make a grease sandwich. A small blob should be sufficient. If you didn't remove the old thermal grease, check how much is on the processor and remove any if possible.

6. Reseat and retest


Put the cooler back in its home and wiggle it in place a little to make sure that the thermal grease is spread evenly between the cooler and CPU. Next, clip the retaining arms or pins back into place and reconnect the fan to your system.

Boot your machine and run the same tests that you originally did. If your CPU is still running too hot then a new cooler is needed.