If your PC quite literally never fails to make itself heard, you might want to take a look at the usual suspect for persistent fan noise: Your CPU cooler. Here's a detailed, visual guide on how to replace it with something better and what to keep in mind.

Be it turbo mode, hyper-threading or even multiple cores – modern CPUs have come a long way since the inception of very first microprocessor. And though ever smaller manufacturing methods have greatly helped to keep temperature emissions in check, the corresponding development of “boxed” CPU coolers has been somewhat less spectacular. Even today, neither Intel nor AMD bother to equip their processors with anything more than what is absolutely required, leading to unnecessarily high temperatures and relentless fan noises, slowly chipping away at the sanity of PC users in those midsummer days. 

It is probably common knowledge that the most effective and permanent solution to this torment is to upgrade to a bigger and more sophisticated CPU fan. Somewhat less obvious, however, are the exact steps on how to do so. Here's what you need to keep in mind and how to make the operation go smoothly. See also: How to upgrade a PCs processor

Choosing the right CPU cooler

In order to find a compatible model, you will first have to find out what kind of socket your CPU uses. This can be easily accomplished by downloading and installing the nifty hardware utility CPU-Z. Fire it up and look for the field “Package” under the tab “CPU”. This will give you the exact specification of your mainboard socket - for example “Socket 775 LGA”. Note it down and make sure that your future cooler supports this particular format (more expensive coolers are often compatible with multiple different sockets).

The coolers themselves can come in many different shapes and forms, typically starting as low as £ 5 and going all the way up to £70 depending on the quality, manufacturer and popularity. Which one you should choose differs from socket to socket and is ultimately up to you. It's almost a given however, that anything beyond £15 will easily upgrade your stock cooler. Obviously, we recommend reading some reviews to find out which one works best for your specific system and budget.

Additionally, size matters – at least in terms of cooling. While professional fan models can easily be twice the size as their boxed counterparts and might seem excessive at first, they are much more efficient at dissipating heat away from the processor due to their greater amount of metal surface – also called “heatsink”. Thus, if you are planning on buying a rather “prominent” cooler, you might want to compare its measurements (particularly the height)  with the actual space of your PC case to make sure it fits inside.

Note: Though the boxing of most coolers typically includes a small amount of thermal paste, its quality can diverge wildly, thus potentially mitigating the cooling performance. If you want to go the extra mile and make the most out of your new cooler, see if you can you can get your hands on some high-quality ceramic or silver-based thermal compound (particularly fancy mixtures might even include diamond dust).

Also take a look at: Overclock your CPU, GPU and RAM

How to replace your CPU cooler

To get started, shut your system down and flick the switch on the back of your power supply to “Off” (which can itself be accessed from back of your PC). As this is going to be a fairly elaborate endeavour, it's a good idea to remove all cables from your computer and lay it down an an flat and well lit surface for easy access.

Also, make sure to ground yourself on a metal object before proceeding (such as your radiator), and try to steer clear from carpets (and other objects that might charge you up again) for the time being.

1. Open your case from the side to get a good look at the insides of your PC. Many coolers require the installation of a backplate on the other side of your motherboard to stabilize them. If this applies to your model, you will likely have to remove the motherboard itself to reach the right spot - start by removing potential screws that might hold your graphics card in place. If not, jump to step 7.

2. While older models can be pulled out from their PCI slot without any further mechanisms, most modern graphics cards require you to pull a small plastic level on its side. Some may even be connected to your power supply directly with one or two 6-pin connectors. Unplug them and remove the card.

3. Next, look for the screws that are keeping your motherboard attached to the PC case. Simply, check the borders to find the lot of them (the last one is normally located just below your CPU in the middle). Try to loosen them all at roughly the same rate until they can be removed.

4. Unplug all cables connected to your motherboard that are interfering with the removal. If you aren't sure whether or not you can reconnect them properly later on, its a good idea to make a photo while everything is still in place. Marked in our photo: The 24-pin and 4-pin power supply connectors and the SATA slots.

5. Typically, there are nine screws to be removed from ATX motherboards, though this may vary with other form factors. Make sure you got them all and put them someplace safe for the time being.

6. Carefully lift your motherboard out of the case. It's up to you whether or not you want to remove all cables from the motherboard, as this might overcomplicate the re-installation for dexterous tinkerers. For maximum comfort, it's obviously better to do so and to take the motherboard someplace else.

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7. A close up of our old CPU cooler – already a bit dusty. Notice the small size of the fan blades.

8. Look for the small 4-pin cable that extends from the cooler to the motherboard. Gently waggle it off without bending the pins.

9. Next, you will have to remove the cooler itself. See if there's a small lever at the side to push down. Depending on your respective model, the exact method of removal might differ. If there's no lever to be found, you can typically find four push-pins at each corner.

10. After pressing down the lever, release the metal clamp from both sides of the cooler. If you are dealing with push-pins instead, try turning your motherboard around and see if your can squeeze the two halfes of each pin together in order to loosen it.

11. On the left: Our new “Scythe Mugen II” (about £35); on the right: The old boxed cooler.

12. As you will have noticed, your CPU is now finally brought to light. The greasy paste on top of it is a thermal compound that improves the heat conductivity between the CPU and the cooler, thus improving the cooling performance (air alone would be significantly less effective). Refrain from touching it and ignore it for now.

13. If your new cooler requires you the install a backplate onto your motherboard, turn it around and do so.

14. Additionally, take a look into the manufacturer's manual and see if there are instructions as to how the cooler needs to be modified before being placed onto your respective socket. This typically includes assembling the mounting device in a particular fashion.

15. Attach the fan to the heatsink. This is often accomplished with the help of metal brackets.

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16. Time to get back to the CPU. It is highly advisable to remove the rest of the old paste before applying a new dose. Carefully wipe the bulk of it away with a clean piece of cloth.

17. Next, take another piece of cloth and slightly moisten it with pure or rubbing alcohol (at least 70%+). Gently sweep the surface of the CPU with it a couple of times to remove all residues. Take care not to accidentally touch the surface, as this will likely leave greasy fingerprints.

18. Apply a tiny dose of fresh thermal paste - a bit smaller than the size of a pea - on top of your CPU and evenly spread it with the help a a strong sheet of paper (business cards will do). The idea is to thoroughly cover the whole surface while keeping the layer as thin as possible to ensure ideal cooling conditions.

19. If present, make sure to remove the plastic foliage covering the underside of your CPU cooler. Again, try not to accidentally touch the metal surface with your fingers after doing so.

20. Put all necessary backplate screws in place and rotate the cooler until it matches their position. Gently lower it onto the CPU, ideally without twisting it around too much once it is has made contact. Tighten the screws connecting the cooler to the backplate/motherboard.

21. Once the cooler is firmly connected to the motherboard, make sure it pushes the air out of the rear of your PC case to optimize airflow (whether you place the fan before or behind the heatsink is up to your model and preference).

22. As a final step, put your motherboard back into the PC case and reattach all necessary screws as well as the cables and PCI cards that you previously removed. Don't forget to connect the fan power plug to the 4-pin connector on the motherboard before closing it up again.

Testing your new setup

If everything has gone according to plan, your new and improved PC is set to go. Power it up and you will likely soon notice a significant reduction of fan noise. To check if the new setup remains stable ready under a high performance level, you should put it under a stress test. Download Prime95 as well as SpeedFan to give your CPU something intensive to work on while measuring its peak temperature.

Open both programs and trigger a testing routine under Prime95. After about 3 minutes, the temperature should start to flatten out (if it goes as high as 90°C or more, cancel the test, as something has likely gone wrong during the installation). Note the results and exit Prime95 by closing it from the taskbar.

This might also be of interest: How to benchmark your PC for free

Its a good idea to compare the final temperature with similar hardware setups from the internet to see if your cooler can compete with general standards. As a rule of thumb however, anything below 70°C is fine and anything under 60°C is quite good.

Note: Prime95 is one of the most intensive stress tests that are available for CPUs and will push them well beyond everyday boundaries. Thus, don't worry if your new fan starts to make itself fairly audible during the test, as your PC won't have to deal with comparable workloads in everyday settings and will likely stay much quieter – even while gaming.