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How I make PC's become silent






A lot of PC's make a significant amount of noise when they are turned on. The hard disk makes the case shudder, the processor and power fan constantly emit a fuzzy roaring. This may not be a problem for a lot of users, but it can be a real problem for others. Here are some tricks I used to decrease the noise, sometimes even make it completely disappear.


Be careful

Some internal parts of a PC use high electric tensions, 110 Volts or 220 Volts. This is dangerous. Switch the computer off before touching parts inside. Actually just switching the computer down is far not enough. The only real protection is to pull the power chord from the mains away. Note some PC's on a lan/network can get high tension from the network cables themselves. In such case pull the network cables out too, before pulling out the power chord from the mains.

Computers are sometimes very fragile. Everything you do to a PC can destroy something inside it. Even just opening and closing it. Be prepared to have to pay for another sound card or another motherboard.

When doing something to the ventilator of a processor, keep in mind most processors really need to be cooled down. Without adequate ventilation they can burn in a few minutes or at least stop working. Keep also in mind the energy consumed by a processor (and thereby the amount of heat it produces) depends on what it is doing. Most of the time a processor does virtually nothing. It just performs short calculation bursts in order to start a program, calculate a printout or redraw a window. In such circumstances the air at the output of the cooling fan of my processor is cold. But when you make it perform heavy calculations during lenghty minutes, the air at the output can become really warm. The amount of electric power my processor once consumed even made the electric supply of my PC overheat and go down! I had to get a stronger power supply.

Most computers have safety mechanisms against shortcuts and other mistakes like plugging connectors the wrong way. They simply switch off or hang at boot-up. Once the problem is fixed, they will work back like before, with no damage. If this happens while your are hacking inside your computer, it means you did a big mistake and should let somebody else do it for you or do it with you.

If your computer software start crashing and hanging after your interventions, a probable explanation is you did something that prevents a part inside the computer to be cooled down efficiently. This is bad.


Simply tunings

Sometimes no screwdriver nor soldering iron is necessary. A friend's computer was making a heavy ventilator noise. This was upsetting since at the shop where he bought the computer it was noiseless. Actually the problem was the shop environment was cold and my friend's room was hot. So the processor was a little hotter and the motherboard decided to switch the processor ventilator to maximum speed. Solution was to tune the motherboard BIOS settings. We told the motherboard that the processor should be allowed to run at a slightly higher temperature. Default setting was 50 C° and we allowed 60 C°. Motherboard BIOS settings are very easy to tune for an experienced technician. Just press the Del key at startup and use your mind. If you aren't experienced maybe best abstain. (A few months later my friend's computer started to hang once in a while and he had to lower the temperature back down to 50 C° and endure the noise.)


Cooling fans

There are two kinds of fans: noisy ones and silent ones, depending on how they were build. If you can, just replace a noisy ventilator with a silent one. Be careful: some ventilators are slower because they blow less air, so they will cool less too.

On some PC's I just switched the power supply ventilator off by cutting its wires (and wrapping them inside insulating materials) or I put a small iron wire through its blades, from the outside. This can only be done on PC's with a big power source and a motherboard that consumes almost nothing, like early i386 PC's or some Mac boxes. Then the power source and the PC inside do not need the hot air be blown away. In order to test for this, lock the ventilator for a few minutes then let it turn again. If the air that comes out is cool or just tepid, maybe you can assume the ventilator can be switched off forever. This trick can destroy your computer or make it hang. Also you need to take into account the fact the computer produces much more heat when the processor needs to perform lengthy calculations.

Most frequent intervention is I put diodes in series on the power wires of the ventilator. Each diode lowers the electric tension the ventilator receives of about 0.7 Volts. For example, 2 diodes put on a 5 Volts power source make the ventilator receive just 3.6 Volts. This makes the ventilator turn slower. The air flux reduction is not very important yet the noise reduction can be remarkable.
An intervention I once did was to glue some pieces of plastic, paper or cardboard to the ventilator blades. This slows them down just like the flaps of a plane. Cleverly placed blades make the ventilator blow roughly the same quantity of air while turning significantly slower and with less noise.

Some recent processors that are placed vertically on the motherboard are enclosed inside a black plastic box together with a ventilator. The one a friend gave me was really very noisy. So I tear the plastic and metal box apart, threw the box and ventilator away, just kept the vertical printed circuit with the processor and the peripheral circuits on it, and put a standard heat sink & ventilator on the processor, latched with silicon heat paste and a cotton string. (Be careful, just aiming a ventilator at the processor surface is not sufficient. The heat sink is necessary because it takes the heat away effectively and distributes it amongst a forest of fins, where it can be taken away by the slow air flux of the ventilator. In order to be able to use no ventilator, less air should be used but at higher pressure, forced above the processor surface between the processor surface and a close plate.)

Provided the processor does not produce too much heat the little heat sink & ventilator can be replaced by a huge heat sink and no ventilator. Maybe even a sort of little chimney can be used to make the air move due to the heating. This is expensive.

My P4 processor was cooled down by a little ventilator powered with 12 V. I replaced it by a huge yet standard 12 V ventilator and I powered it on 7 V. With such a low tension feed and low turning speed it is virtually noiseless. Yet it seems to output the same as the little noisy ventilator since the processor remains cool under any circumstance. Good deal. Yet a lot of cardboard cutting and taping to adapt and duct the big ventilator.

While you're playing with ventilators, maybe check the temperature of your motherboard chips, graphic card chip and hard drive. Those parts sometimes really benefit from a little ventilation. For my PC I bought two standard PC 12 V ventilators for a few € and I powered them with only 5 V. They turn very slowly, making no noise. I directed them towards the graphic card and towards the hard disks. That makes them cool down a lot at virtually no cost and no noise.

I recently discovered that a ventilator makes much less noise if it aspirates the air from the radiator instead of blowing the air towards the radiator. I wrote a Web page about this.


The hard disk drive

Hard disks produce noise two different ways:
Some computers can be tuned to have the hard disks be switched off when they have not been used during a few minutes or tens of minutes. Problem is they will need a few seconds to automatically switch back on when they will be needed back. This can be tuned through the BIOS tune screen at start-up (generally called by pressing the Del key down) or through the operating system control panel (power management).

Most of the noise the user hears are vibrations the hard disk transmits to the rest of the case. My favorite trick is to unscrew the hard disk and let it hang inside the computer, just latched to its power and data connection wires (latched somewhere). Of course this is not responsible way of doing, it is only for people who are computer freaks and know they will have to fasten their hard disk back in place before moving the computer. More serious is to latch the hard disk somewhere inside the computer through several thin nylon wires. Just like a bug caught in a spider web.

When it is possible, the hard disk drive can be enclosed inside a box, its wires coming out of the box through thin holes closed by foam or the like. The hard disk can be held inside the box by some little pieces of foam glued to the box. Be careful: the box must not allow the hard disk to heat up. Best do this with hard disks that keep cool naturally, put a ventilator inside the box (like Russians did inside space probes), use a box that lets heat flow away (thick aluminum boxes, for example) or use a big box (an old fridge, for example).

Most of the noise a hard disk drive makes a PC produce is transmitted by the computer case. So using a more solid computer case, with thick metal or plastic armature and faces, will probably help. Car furniture shops sell thick gummy plates that are intended to be glued inside hidden car parts to lower the vibrations and noise, perhaps this could help too?

This evening I'll try to put my hard disk inside a good quality plastic bag and the whole inside a little bucket of water. The plastic bag opening and the hard disk wires coming out of the water. Very silly, but I thing it will give excellent results. (It did !)


CD-ROM drives

I never tried to make a CD-ROM drive become silent. All of them are perfectly silent when they are not being used. Only some high speed ones, 24x and above, roar when they are being accessed by the computer. But while I was repairing one I could notice following facts:

The small round plastic & steel piece that comes above the CD to latch it on the motor's axis was build a wrong way. When a CD is in and the round piece is glued on it by the magnetic force of the motor's axis' magnet, the piece is able to move sideways a few millimeters. This is the open door to vibrations, due to the excentricity of the part. I suppose the round piece had been conceived to match exactly on the motors' axis when there is no CD inside.

There is a big fork-shaped iron plate above the CD, the purpose of which is to hold the small round piece. It makes the round piece move a little upwards and downwards when a CD is pushed in or out. When a CD is turning inside the CD-ROM drive the fork should not touch the round piece, letting it turn freely. That CD-ROM drive's problem was that the fork-shaped plate actually strongly touched the round piece, pulling the motor's axis a few degrees away. This made the CD-ROM drive produce noise and at the end even no more allowed it to turn properly. I mend this by constructing blocks with two-components hardening paste. The fork is now obliged to stop exactly in a well-given position when a CD goes in. There is no more contact between the two pieces when the CD turns. The round piece only touches the CD and the motor's axis. From then on the CD-ROM drive became perfectly silent.


Global approach

Sometimes the best solution to avoid the noise produced by a computer is to put the computer further away. Below the table or a few meters away, inside a big box or in another room. Cables can be found in computer and electronic parts shops to allow the keyboard, mouse and screen be connected to a remote computer. The longest connection distance between computer and monitor I made was about 200 meters (not because of the computer's noise).

Silent computers or computer parts can be bought. Most yet not all recent hard drives are almost noiseless. Also lots of CD and DVD readers and writers. Expensive power sources make their ventilators turn very slowly and only power them up when there is a danger of overheating.

These are links towards other pages about PC noise reduction and companies selling components :

CG Consultant BV
Quietpc.com
The Silent PC
Silent PC mailing list
Silent PC Review
Enjoy the Silence
NoiseLess Linux (French)

Lend your processor power for valuable scientific research: http://boinc.berkeley.edu



Eric Brasseur  -  March 1 1999  till  April 16 2006
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