▷ Passive power supply: pros and cons

Choosing a power supply for our new PC is a very difficult task, since the market offers us a huge variety of models with different characteristics. To make it even more complicated, passive power supplies have appeared in recent years, promising to run completely quietly by removing the fan. In this article we are going to see the advantages and disadvantages of a passive power supply.

Index of contents

What is a passive power supply

Passive power supplies are not really a new thing, although more and more models are available to meet the needs of those allergic to fan noise. Initially these sources were aimed at a very specific audience, although more and more users are looking for a silent PC. Passive power supplies aim to eliminate the fan, without compromising its operating temperature, something that is not easy to achieve in a component that generates a significant amount of heat.

Semi-passive power supplies have been born in recent years, these have a fan, but include a passive mode of operation, which keeps it switched off until the load and the temperature of the source reaches a threshold defined by the manufacturer. At this point, it should be noted that most active power supplies, that is, with a fan that is always spinning, include a technology capable of automatically adjusting the speed of the fan's rotation depending on the need for cooling. This makes these sources very quiet in low-load situations, and higher-quality models stay quiet even under load.

Advantages of passive power supplies and their characteristics

A passive power supply is the definitive solution for users who do not want to have any kind of noise on their PC, those who also use passive heatsinks on the graphics card and processor. These passive power supplies must meet specific characteristics in order for them to function correctly:

High energy efficiency: energy efficiency is a reflection of the amount of energy that is lost in the form of heat during the operation of an electronic component. The higher the energy efficiency, the less energy will be lost in the form of heat, and therefore less the component will heat up. Therefore, passive power supplies must have the highest possible energy efficiency, with 80 Plus Gold being the minimum, although better if it has an 80 Plus Platinum or Titanium certificate. Great build quality - Even if energy efficiency is very high, passive power supplies will always tend to heat up more than active versions. Due to its higher operating temperature, it must be built with the highest quality components, as it is the only way to guarantee its good operation and maximum reliability. Optimized internal design: the placement of the electronic board is also important, in this type of power supply, the electronic board is placed on the bottom. This is because hot air is less dense than cold air and tends to rise above it. By placing the electronic board at the bottom, convection of hot air towards the top is favored so that the outside of the source comes out.. These types of fountains have a grille at the top, in this way the hot air has the maximum facility to escape.

Disadvantages of passive power supplies

To all this, it must be borne in mind that the internal air flow of the PC will be more important in the event that we want to mount a passive power supply, since otherwise it will be easier for the heat to accumulate inside the equipment and cause overheating of the other components.

Keep in mind that no matter how good the air flow inside a PC is, it will be very difficult for a passive power supply not to cause a higher internal temperature, especially in the case of powerful equipment that consumes a lot of energy. These sources will limit the hardware that we can mount, since putting a very high-end graphics card and a very powerful processor generates a lot of heat that will affect the power supply in a negative way.

Another disadvantage of passive power supplies is that their price is much higher than the active ones, since models that barely exceed 500W can have a price of more than 120 euros, a figure for which we can buy a much more powerful and active source. keep it very quiet.

Is a passive power supply worth it?

This is a very difficult question to answer, since it depends on what each user wants. If you want a very powerful computer, with the best graphics card and the best processor on the market overclocked, there is no point in mounting a passive source, since the graphics card and the processor heatsink will generate much more noise than a source of active feeding. In this case it would be better to opt for an active source, which will also be cheaper and we can invest more money in other components.

Let's take a practical case: one of the most important passive sources today is the Seasonic Prime Titanium Fanless 600W. This model has an extremely high price when reaching 220 euros. Although it is indeed a model of the highest quality and efficiency, we value the alternatives from 3 bands: semi-passive sources Titanium, semi-passive sources Gold / Platinum and active sources Gold / Platinum.

At the same price as the Prime Fanless we have ranges such as the Enermax MaxTytan with 800W of power, capable of keeping its fan off up to 55% load (440W) and operating at extremely low revolutions per minute (550rpm) up to 80% load (640W). With such a source, we would still have an absolute silence experience most of the time (or all of it) with Mono-GPU equipment, and its power would allow us to overclock and mount more 'extreme' configurations with extremely silent operation most of the time. weather.

In lower price ranges and sacrificing Titanium efficiency but maintaining or improving quality and functionalities, there are sources such as the Corsair HX750 or HX850, which are priced at around 150 to 160 euros and again maintain ultra-aggressive semi-passive modes that, Thanks to the high quality of their fan, they will hardly be noticeable once they start up. In ranges already much cheaper (we drop from € 100) we have the RM550x of the same Corsair that maintains these characteristics.

Finally, from the range of active sources (which are an important plus in their cooling) we have the Be Quiet! Ranges Straight Power 11 and Dark Power Pro 11, which are totally inaudible except at minimum distances thanks to their fan Top-quality SilentWings 3 that spins at extremely low revs, below 300 or 200 rpm

In any case, if you want equipment that is quiet and sufficient for day-to-day tasks, a passive power supply can be a great idea. A clear example of this situation is the office equipment, an environment where silence is desired and the tasks to be performed do not require very powerful hardware. Another example may be a small Mini ITX equipment to have it in the living room and watch movies and series, in this case we can choose a processor with very low power consumption that will hardly heat up.

Surely you are interested in reading the following guides to have a silent PC: