How to replace a fan in a power supply

Sometimes the fan on the power supply unit, especially if the model is a budget model, begins to crack after several years of operation, making using the PC extremely uncomfortable, or completely breaks down, jamming and causing overheating. Let’s figure out how to choose the right replacement fan and how to reliably install it with minimal technical skills.

Why fans in a power supply fail faster than usual
Fans in a PC power supply operate under much more severe conditions than conventional case fans. Firstly, fans with sleeve bearings and hydrodynamic bearings, which are massively installed in power supplies, are extremely adversely affected by horizontal installation. The grease in the bearing in this position gradually flows out through the shaft seal, causing the sleeves and shaft to wear out quickly.

Secondly, the high temperature in the power unit, which can be higher than 70 degrees, also contributes to liquefaction, evaporation and rapid leakage of the lubricant through the seal. An increase in temperature by 20 degrees reduces the service life of such bearings by a factor of three. Thirdly, increased fan speed contributes to rapid wear and tear, with which manufacturers compensate for savings on cooling radiators and high-quality electronic components in a budget power supply.

As a result, the fan in a budget power supply unit begins to crackle and vibrate after several years of operation due to bearing wear. Lubricating the fan bearing does not help for long as it does not eliminate the cause of the noise. Rolling bearings, which sometimes have poor build quality and begin to make noise immediately, on a completely new device, are not immune from rapid wear and tear.

Characteristics, specifics of operating modes and types of connection of fans in the power supply

Modern power supplies usually use 120 and 140 mm fans, while budget models with low power use 80 mm. You can often find non-standard sizes: 135 or 139 mm, which can be a problem when replacing them. You can find out the exact size of the fan from the reviews of the power supply , and if you can’t find a suitable one, you can compensate for the small difference by attaching it through silicone nails.

A fan in the power supply is usually connected with a two-pin connector, and given that it is almost impossible to find such fans on sale, we will have to choose a model with a three- or four-pin connector and replace it with a two-pin one. With this connection, the fan is controlled by voltage regulation, and the rpm is not read, since the rpm-voltage dependence is set in the fan controller of the power supply.

There are models of power supplies where control is performed using PWM technology and special proprietary connectors are installed. In the most budget models, the fan wire can be soldered and have no connector at all.

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One of the most important characteristics of the fan for us will be the number of its maximum revolutions, because if we replace the fan with a low-speed one, the PSU fan controller will not know about it, and the revolutions will drop noticeably, which will cause the device to overheat. A fan with higher rpms will make the power supply noisier, but given that it will get colder, this option can be considered as a working one.

The starting voltage of the fan is equally important – in power supplies it is usually low, 4.5-5V, to allow the high-speed fan to start and run at low speeds. If you put a fan with a high starting voltage in the power supply, it simply will not start in a low load mode on the device, causing overheating, because conventional models are not designed to work in a passive mode. You can find out the starting voltage in the fan characteristics.

 

The most common option for controlling a fan in a power supply is its dependence on the power consumed by the device. Consumption rises – temperatures inside the power supply also rise, requiring increased fan speeds. In more advanced models, the fan also reacts to the rise in temperature inside the device.

 

You can find out the dependence of the fan speed on the load on the power supply from the reviews . Usually we will see a graph where the developers tried to create acoustic comfort at light load and a smooth increase in fan speed with increasing load. Power supplies with a semi-passive cooling system do not start the fan under light load, allowing for a very quiet system.

Choosing a replacement fan

When choosing a replacement fan, you should first look at models with low starting voltage and pay attention to their maximum speed. If they are slightly larger than the fan of the power supply being replaced, it will result in lower temperatures of the device, although it will increase the noise level. And if you are sure that there will be no overheating, since your power supply is only partially loaded, then you can install a fan with lower speeds – this will give a lower noise level.

It is also logical to choose the option with higher speeds because fans with high static pressure are usually used in power supplies – they are distinguished by wide massive blades. Fans with high airflow but low static pressure are more common on the market. Thus, it will be difficult to blow through the dense internals of the power supply, which can be compensated for by higher rpm.

 

It is worth paying attention to the fan bearing purchased for replacement. Better give preference to models with hydrodynamic and ball bearings, as the most durable. And the last thing to consider is the price of the fan – a high-quality model may cost more than your PSU, but it is impractical to put it in a budget PSU.

According to the characteristics described above, the Arctic Cooling P12 PWM and P14 PWM fans are perfect for us: they have a low starting voltage and a fairly high maximum speed in combination with an affordable price.

Fan Arctic Cooling P12 PWM [ACFAN00119A]
750 *
Fan Arctic Cooling P14 PWM [ACFAN00124A]
899 *
How to replace a fan in a power supply – practice

Important! To replace the fan, you need to power off the PC and remove the power supply from the case. Remember that PS high-voltage capacitors retain their charge for a long time and there is a risk of electric shock when manipulating an open device. It is advisable to let the power supply lie down for two to three days in the off state before replacing the fan and be careful when handling it.

For example, we will replace the fan of the Chieftec CFT-700-14CS power supply. The fan in this power supply cracked at first, and then stopped starting altogether. This is an old model and there is not even a review of it on the network, but the same fan produced by Yate Loon is installed in the younger model – Chieftec CFT-600-14CS and has just such a dependence of rpm on power.