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Are you looking to assemble a Custom PC, and finding out how to calculate energy consumption seems complex? In this article, I break down the various information you need to know before embarking on the assembly of a Custom PC.

How powerful are PC components?

A PC’s power consumption depends on the type of component and its power.
For example, a gamer PC will consume much more power because its components are more powerful than an office PC.

Custom PC componentsPower requirements
Motherboard25 – 100 W
CPU / Processor55 – 150 W
GPU / Graphics card25 – 350 W
HDD hard disk0.7 – 9 W
Solid-state drive (SSD)0.6 – 3 W
RAM2 – 5.5 W
Housing fan0.6 – 3 W
CD / DVD player15 – 27 W
CPU fan5 – 10 W
PC component power requirements

What is the average power consumption of a computer in watts?

A computer’s power consumption can vary considerably depending on the power of the processor, graphics card, connected peripherals and so on.

A PC’s power consumption can range from 300 Watts to 1250 Watts.
The average power consumption of a computer is around 550 Watts.

Office automation300W to 650W
Gamer550W to 1250W
Laptop PC45W to 120W
Average PC power

How to calculate the energy consumption of a Custom PC?

As you’ve seen, PC power consumption is extremely variable, and there’s no room for randomness in this area.

Let’s take the concrete example of a computer on Mesure :

MotherboardGigabyte B760 Gaming100 W
CPUi5-12400F117 W
SSD M.2Crucial P3 Plus 2TB10W
Graphics cardMSI GeForce RTX 4060 Ventus 2X Black 8G OC135 W
RAM (X4)Crucial DDR4 3200MHz 4x16GB(10W x 4)= 40W
CPU fanBe quiet Pure Rock10 W
SecurityAdd 20% of total412W + 20% = 494.4W
A 550W power supply is sufficient

Advice: always go for the highest variable, as it’s better to have a more powerful power supply than a less powerful one. In addition, think about possible upgrades so you don’t have to invest in a new power supply when upgrading your computer’s components.

What is the risk of a lack of power from the power supply?

  • System instability : If the power supply is not sufficient to power all PC components, this can lead to instabilities such as system crashes, unexpected reboots or hardware errors.
  • Overheating : When the power supply is unable to deliver sufficient power, some components may operate at unstable voltages, causing the computer to overheat.
  • Component damage : Under-feeding of components can lead to premature wear and component malfunction.