PSU meaning and How to Choose the Best for Your PC?

PSU meaning cover image

PSU is one of the most important yet one of the most ignored components of PC. While making a PC, gaming, or productivity-focused, people just tend to add a PSU because it is needed, but what is the meaning of PSU and what are the things you need to know before adding one? PSU stands for Power Supply Unit and this device moderates, converts, and smoothens the eclectic power from the wall socket to your PC. 

PSU is an absolute necessity if you want to run your PC. It is everywhere, in all-in-one desktops, laptops, everywhere. Even the wall adapter for your phone has one. This necessity arises from the transmission of current from the power station and the requirement of devices. We’ll elaborate on that in the next section. 

What this article holds;

  • What is PSU and why it’s needed 
  • The jargon of PSU; ATX, ATX 12V, PCIe ports, colored cables, wattage, etc.
  • How to check which PSU is right for you
  • The size and placement of PSUs

What is PSU and why is it need?

Power supply units are compound devices made of different components. These components include a transformer, rectifier, filter, and regulator. This is joined by an array of wires and other smaller components which we’ll leave to prevent complicating the subject. 

The foremost need for PSU is because of the type of current that we use. AC or alternating current is how current is sent from the power grid to your home. This minimizes power loss but the current fluctuates (alternates in waves). This current cannot be used by devices. Almost all electronic devices such as phones, TVs, computers, laptops, etc need DC or direct current to operate. 

A PSU converts this AC current from the socket to DC current to be used by the smaller devices in the PC. The rectifier in the PSU converts AC to DC. Without a PSU (with rectifier) one cannot just plug-in the PC and start using it. I don’t know if I’ll ever get to say this (at the risk of getting edited out);

It is the conversion of AC to DC that lets you run your PC so that you can listen to songs…by ACDC.

– Writer of this article

AC to DC is not the only thing the PSU does. The transformer inside the unit changes the voltage from the socket to the required value to run the device. AC is very non-linear in terms of current with frequent spikes of voltage. This is managed and smoothened by the regulator. The filter in the PSU further smoothens the input to ensure the safe and efficient functioning of the PC components. 

ATX, ATX 12V, PCIe and their relation with PSU

All these terms such as the ATX, ATC 12V, or the PCIe associated with the PSU is about the connecting wire. While diving deeper into these topics might be quite overwhelming, we’ll just touch over these briefly so that you get an understanding of these cables. You can read more about them here.

ATX cables and ports: ATX is a standard that was made by Intel in 1994 to make sure that manufacturers can make PSU that works well with the motherboard requiring a variable amount of current. Like 3.5mm jack used to be the standard for headphones jack. The ATX included a 20-pin connector for the motherboard. There are three types of wire (or rails) with different voltage capacities; +3.3V, +5V, and +12V. The 3.3V was used for newer, more efficient chips while the 5V was used as a standby power supply. As the motherboard and the PC started getting powerful, ports had to be upgraded. 

ATX 12V: The upgraded version of the ATX standard was the ATX 12V (there are many versions of this, current being the v2.4). The CPU started getting more powerful, needing more power. Intel then changed the voltage requirement for the Pentium chips to 12V and this standard was created. 4-pins were added to the connecter in addition to the 20-pins, making the total 24-pins.

The different version of the ATX 12V is just to accommodate the addition of other power-hungry components such as the graphics unit. Do note that the CPU and GPU work on the +12 volts rail of the PSU. So when buying a PSU, make sure to see the wattage of these rails and not the overall wattage since this is what matters the most. 

PCIe slots wire: Modern PSUs also come with 6 or 8 (8 currently) PCIe cable. What is PCIe? PCIe stands for peripheral component interconnected express. These are slots on the motherboard for your graphics cards, SSDs, RAID cards, sound cars, etc. All the peripheral cards that are needed. To supply power to these slots (which are very power-hungry, hogging up as much as 75-watts of power), the PCIe cables are added to the PSU. 

80 PLUS certification: This certification that’s termed as “Gold”, “Silver”, “bronzer”, etc are indicative of the efficiency these PSUs are capable of providing at different power loads. In simple terms, how much power can they actually provide when the components ask the PSU.

For example, if the GPU is asking for 100% of the power supply, if the PSU delivers 90% total, the efficiency will be 90%. This certification lets us know which is the most capable PSU. Here’s a table to let you know what 80 PLUS means;

% of Power demand10%20%50%100%
Gold 87%90%87%

Cabling and fans: Many PSUs come with an option for braided cables with colors. These are just for aesthetic purposes. Different cable configuration ranges from clean look to colored galore. 

PSUs also have a fan inbuilt. This is necessary since the PSU is dealing with current, heat will be generated. The fan is always placed away from the components, usually behind the tower. This is changing since the external wires are exposed to the heat from the fan. Modern CPU cabinets or chassis have the fan placed at the base of the tower. 

Image of a PSU

How to buy the right PSU?

The market is filled with PSUs with different power capacities. Which one to buy is a dilemma many people get into. Here are some tips for buying a great PSU that meets your requirement.

  • It must be from a reputable brand. Some of the best PSU makes are Corsair, Antec, SeaSonic, etc. Corsair is our recommendation because they make really good PSUs (we are not sponsored by them). 
  • Check the wattage or the power capacity of the PSU to make sure that it can handle the requirement. Do note that the PSU capacity must always be higher than the overall requirement. So if your PC needs a 500-watts peak, buy a PSU that can deliver 700+ watts of power. This is to ensure a smooth power supply, no overheating or overload, and failure. You can calculate the power requirement here. 
  • Another thing to notice is to check if the 12V has a higher wattage capacity. The 12V rail is the important rail used to run the processor and GPU. Companies show the overall watt capacity while the 12V rail has a lower capacity.
  • It has the 80 PLUS certification (preferably Gold) and if you are building a high-end PC with the powerful graphics card, go for a better certification (refer to the table above). 
  • It must have at least 3 years warranty to ensure that your money is well spent. Some PSU costs as high as $600! Expensive PSUs usually come with a 5-year warranty so make sure if you spend more, you get more years for the warranty period. 
  • Read reviews of the PSUs and see what the average verdict is regarding the performance of the PSU. Anything above $200 will offer a decent PSU, but reviews are always helpful. 

This concludes the article about PSUs. We hope it was helpful and got your query resolved. You can read more articles that are somewhat related to this topic.

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