Replace your AMD/Intel fan. The benefits are work the effort and money.
Most Intel and AMD processor chips arrive with a free fan. The free fan is designed to be small so it will fit any combination of motherboard and case. There are lots of better designed fans producing less noise while using less energy or increasing the cooling. Why, when, and where should you use the other fans?
Noise is bad. The noise from moving parts in machinery does damage your hearing. The constant whining of fans in computers will decrease your hearing over the years. After about 15 years of working with computers on desktops, I had hearing loss in the frequency range of the default fans in desktop and server computers.
I was exposed a bit more than most people because I did work with test computers. I might have two or more computers on my desk at any one time. You are exposed less but you are not safe, the damage just takes longer. The fan noise reinforces the noise damage from vacuum cleaners, the cooling fans on laser printers, and a huge range of other sources including badly designed air conditioning. They all add up. You can reduce the impact on you, your family, and friends by replacing the fans on any computers in the same room as you, your family, or friends.
The lowest cost time to replace the fan is during assembly of the computer. When you buy a new computer, you can order made to measure computers from a number of suppliers and they will use an alternative fan if requested.
When you buy a brand name computer prebuilt, you lose your guarantee if you replace the fan before the guarantee runs out and by then it is often time to upgrade. The big brands are not interested in making one computer quiet just for you. You might be able to change their mind if you are buying thousands of computers for a company. I negotiated with one manufacturer for a very good system when the order was over 600 computers. My customer then decided to buy 200 at a time and the manufacturer severely limited the changes they would make for a batch of 200.
Dell and some other
built to order brands have a pathetically small number of options they will change and none are related to noise. Given that these big brands are often only a $100 cheaper when compared on the quality of the components they use, a person with any knowledge of computer components can get a better deal discussing their requirements with a true made to measure supplier. As an example, one of my customers had several Dell medium cost desktop computers all purchased within a few months, all with the same or similar model names, and all with wildly varying performance. The first one they purchased was fast. The others were slow. The one I used for a day was so slow, it was hard to believe the machine contained one of the fastest available Intel desktop processors of that time. The problem appeared to be the classic cost saving cheat, a fast processor mounted on an incredibly cheap and slow motherboard. If the same machine was ordered from a reputable made to measure supplier, they would use a motherboard costing $145 instead of one costing $75 and the whole computer would be two or three times faster.
A good quiet processor fan is around AU$75. The processor fan is the noisiest fan on most computers. The extra cost works out at seven cents per day over the life of the computer. Your ears will thank you later in life.
The noisiest fan in a games oriented computer is in the graphics card. If you are not playing the latest games at maximum speed, you can use a slightly slower graphics card with no fan. That leaves the processor fan as the noisiest fan. The first place to look for noise is the graphics card, if you use one, then the processor. Look around the processor for available space. The quieter fans will be larger than the Intel or AMD fan. When you have plenty of room, you can choose the quietest options. Smaller computers might fit only an intermediate size fan with less noise reduction than the big monsters.
Line of site
Now look at where the computer resides. Does the computer have a direct line to your ears? If you can see the computer when you sit at your desk, the sound goes straight into your ears and you have to do more than replace the processor fan. Have the computer built using a sound absorbing case.
Behind the desk
When your computer is behind your desk, or in a similar shielded situation, the sound echoes off hard surfaces up to your ears. You can buy a computer assembled in a sound absorbent case (the most flexible option) or you can glue rugs and old carpets to the reflective surfaces to reduce noise. Those old woollen wall hangings used in stone castles should be used on modern apartments with their concrete walls.
In another room
You can put your computer in another room to remove the noise. Your laser printer probably has the most annoying noise so move that first. If you use a NAS device, Network Attached Storage, that can go out to the same room as the laser printer. You could put your computer in the other room and access your computer through a remote connection or a KVM extender.
Placing your computer in another room will make access to the DVD drive and USB sockets difficult. Replacing the processor fan with a quieter fan is easier.
In the longer term, you will replace your current computer and will be able to order something quieter. If you have a specific configuration in mind, I can add some advice on components based on tests. leave a comment about what you are considering buying.