Power supply top or bottom: which is better?

Assembling a new computer has a lot of nuances and subtleties. When buying a system unit, you will have to decide on the location of the power supply. In most cases, the choice is between Power Supply Top Or Bottom placement. What is the difference and what are the advantages of each of the methods we will consider in this material. 

power supply top or bottom
power supply top or bottom

Power supply top or bottom: which is better?

In system units from UltraTower (XL-ATX) to MiniTower (mATX), the power supply is usually located in the rear of the case. However, manufacturers offer a choice – from above or below. In the early 2000s, almost all computers had a PSU on top. However, as components improved, the situation changed, and more and more cases began to appear, where the power supply is installed at the bottom.  Here is article on Motherboard VRM Heatsink.

Power supply top

Why do manufacturers do this? It’s all about heat dissipation. To make it easier for you to understand, let’s compare two types of power supply locations:

The main problem with the top location is that the air intake for cooling comes from the inside of the case. In office builds, this is usually not a big problem, since only a processor with a relatively low TPD is inside. The cooling flow from the front is usually enough to maintain comfortable temperatures. 

However, in the case of a powerful assembly, the situation changes. Inside the case, in addition to the processor with high heat dissipation, other heat sources appear – a video card, motherboard heatsinks, M.2 SSDs, and even RAM strips. If the power supply is installed on top, then it will swallow an already hot stream, practically without cooling. This can be partially compensated by powerful blowing fans, but not in every case.

The solution to this problem was the appearance of cases with a lower location of the power supply. So the designers were able to separate the air flows. The power supply is cooled by outside air, which it takes from the space under the case. 

If you are going to buy a gaming assembly, then a system unit with the lower location of the power supply will be preferable because of the best cooling of all components. 

Power supply Bottom

It would seem that a PSU with a lower location is ideal. So why are top-mounted cases still on sale? This is due to several reasons.

Better dust protection. The main drawback of the bottom-mounted PSU is that it sucks in almost all the dust from the floor. At home, this is not so critical, since you regularly clean. However, somewhere in the office, a PSU with a lower location will clog up very quickly and fail. Filters on the case will help prevent this – many manufacturers produce system units with removable filters. 

Cases with a lower PSU location are not recommended for installation on carpets and other piled surfaces.

The 12V line requires a shorter cable length. Since the pins are located a little closer to the connectors on the motherboard, some wires, in particular the 12 volt line, can be pulled directly without using cable management. However, everything here is individual, depending on the dimensions of the case and the type of PSU. 

More convenient power connection. In tight spaces, it is much easier to plug in the power cord when the jack is higher up. At home, this is not essential, but if you have to service dozens of PCs in the office, then power supplies located at the top of the case are usually easier to interact with. 

Also, some ready-made assemblies are already sold with a built-in power supply unit, which is located in the upper part of the case. For an office computer, this is quite acceptable.  are you confused between ARGB Vs RGB.

Are there other alternatives to power supply top and bottom?

Despite the almost polar division of the market in terms of the location of power supplies in the case, some manufacturers offer non-standard solutions. 

In cubic cases, the PSU can be located in a separate compartment behind the main components. This solution allows you to completely isolate the air flows from the components with a full-fledged partition, and the air is taken from the sidewall. 

A similar solution is the location of the power supply in the front of the case. Despite the common air space with other components, the air is taken from the external environment, and the warm flow is quickly removed by the fans in the upper part. However, due to this location of the PSU, the intake of cool air from the front becomes almost impossible. 

If we talk about typical office assemblies, then some manufacturers also offer the location of the PSU in the frontal area. Cool air is drawn in from outside and blown out through the front panel. The main drawback is that you have to sacrifice free space in the front. This means that the space for installing fans for blowing and baskets for drives is limited. 

There are also more extravagant options. As a rule, they have a large volume of internal space, and the walls of the case do not adjoin closely to each other. This allows you to ensure high-quality ventilation of all components, regardless of the location of the PSU. The main problems are high vulnerability to dust, increased noise and the inability to install filters. 

power supply back at the bottomBetter cooling of components due to air intake from the external environment.
A wider range of housings
High exposure to dust from the floor.
It is unacceptable to place the case on fleecy surfaces
power supply back at the topBetter dust protection.
The 12V line requires a shorter cable length.
Subjectively easier to connect the power cord in cramped conditions
Poor cooling because the air intake comes from the case.Smaller range of cases
power supply at the frontHigh-quality cooling – air intake comes from the external environmentLimited space for front fans and drives.PSU installation is more difficult when compared with other options
power supply in a separate compartmentComplete separation of air flows from the PSU and other components.
Plenty of space for cable management
The boxes are quite large.
Need for long power cables inside the case


In conclusion, it is important to consider where to place the power supply in a computer case. The power supply top or bottom of the case can be used, but there are benefits and drawbacks to each option. Placing the power supply at the top of the case can help keep the internal temperature of the computer lower while placing it at the bottom can make it easier to access. Ultimately, the best option depends on the individual’s needs and preferences.