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26th January 2022 News

“Which PC power supply do I need?” is among the most common questions within the hardware community. This is particularly true when it comes to PC manufacturing, as the power supply is one of the most crucial features of every PC. This is because it’s the sole element that powers each internal module.

Since different power supplies vary in form factors and wattages, it can be difficult to know which power supply is the most appropriate for a PC. Selecting the incorrect power supply can result in instability and compatibility problems with a computer. Consequently, the following factors must be considered when selecting the correct power supply.

Form Factor or Size

Initially, it’ll need to determine which power supply will fit the case. The power supply form factors include TFX, SFX, SFX-L, ATX/PSU, and the typical power supply size is called PS2 power supply or ATX. However, there are still multiple variations in length for the average power supply, even though the height and width are identical.

The typical ATX power supply is 86mm high, 150mm in width, and can vary from 140mm to 230mm in length. TFX, SFX, SFX-L power supplies are among the small form factor power supplies usually implemented within slim cases. A TFX power supply is 65mm high, 85mm wide, and 175mm long. An SFX power supply is 63mm high, 125mm wide, and 100mm long, yet the SFX-L is 130mm long. Another power supply used in the server chassis, Flex ATX, is 40.5mm in height, 81.5mm in width, and 150mm in length. It’s imperative to measure which size power supply you need. Otherwise, it may not fit in the case.

Wattage or Capacity

After measuring the size, the power supply's wattage, power, or capacity will be contemplated. Estimating a power supply’s wattage can be difficult since it requires knowledge about a PC’s total power consumption. However, there are some professional tricks and tools to determine this. These include a PSU calculator or analysing the graphics card power consumption. PSU calculators can be found online to provide a rough estimation of the required power supply capacity. Alternatively, the graphics card requires the most power, meaning the required wattage can be determined by how much power is being used up by the graphics card.

With this being said, it’s a good idea to use a power supply with a slightly higher wattage than necessary, as an underpowered power supply can result in instability problems and burnout.

12V Rail Importance

The 12V Rail’s current will be assessed to determine a power supply output. The 12V Rail is the power supply’s most crucial voltage rail as it’s responsible for powering each of a PC’s key elements. The 12V Rail’s current should be nearly identical to the power supply’s rated wattage. However, if a power supply has various 12V Rails, the current of the single 12V Rails should be added together.

PCIe Power Connectors

A power supply should have a minimum of one 8-pin (6+2) PCIe connector to power a graphics card. However, if the power supply is 500W or higher, two 8-pin (6+2) PCIe power connectors will be required.

Non-Modular vs. Modular

A non-modular power supply has non-detachable cables; however, a modular power supply has a detachable cable that allows cables to be removed or added. Most mid-range to high-end power supplies are modular as they provide organised cable management that results in a cleaner finish. Despite this, budget power supplies tend to be non-modular.


The efficiency of a power supply will also need to be considered. This will be indicated by the six levels of 80 Plus Certification Rating. The lowest level is 80 Plus White, 80 Plus Bronze is next, then 80 Plus Silver, 80 Plus Gold, 80 Plus Platinum, and finally 80 Plus Titanium. The higher the 80 Plus Certification Rating, the better the efficiency and the lower the power consumption. Better efficiency will reduce the customer’s electric bill and the PC’s heat generation.

Protection Features

Any power supply must have basic protection components to prevent abnormal power surges or current variations/voltage. These components include Over Temperature Protection (OTP), Short Circuit Protection (SCP), Over Power Protection (OPP), Over Current Protection (OCP), Under Voltage Protection (UVP), and Over Voltage Protection (OVP). Similarly, braided wires help shield the wires from damage.

Shop Power Supplies with Ideal Power

Here at Ideal Power, we stock all manner of power supplies suited to every PC. Please get in touch, and a member of our expert team will be happy to assist you and walk you through our product range.

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