Getting to Know Your Computer’s Power Supply


The human heart is responsible for pumping blood within the body. Its equivalent part in the world of personal computers is the power supply unit or the PSU. This distributes the electricity to the motherboard and the components that are connected to it. It powers something as small as an Intel NUC mini PC up to your largest towers. But how well do you know your PSU? This is one of the most important parts of your computer, and it is crucial in determining your full system’s upgrade path. If you are in the market for one, here are the essential features that you have to know about.

Form Factors and Other Physical Features

There are different form factors for PSUs available. The most common one is called ATX, and you can find it in most desktop computers. If you want something smaller and would fit in an ITX tower, you have to look for an SFX PSU. It is about half the size of ATX. This is found in many custom small-form-factor builds. What’s even smaller are the NanoATX PSUs. This is a niche product, so you might have a hard time finding some at the market.

Why do you have to care about the size of your PSU? It is all about the wattage. The larger ATX ones top out at about 1000W, which should be powerful enough for a build with top-tier components. SFX PSUs max out at 600W for now, which is still plenty of power. You can probably run a high-end gaming rig with that. NanoATX ones would let you handle about 350W of power, which should be more than enough if you are just using it for office tasks.

Another choice you have to make is if you want to go for the modular or non-modular type. The former has detachable cords for all of its connectors, and this will greatly help if you want clean-looking wire management. The latter has the same functions, except it has its cords connected to the brick itself. If you want to save some money and don’t care about aesthetics, you can go with this.


You wire up your PC’s components to the motherboard using various cables that come included in the package. Two of these are directly plugged into the board, and these are the 12-pin and 4- or 8-pin connectors. The former provides juice to the board’s slots while the latter powers the processor.

The rest of the connectors are plugged into the individual PC parts. The PCI-e connects to your graphics card, while the SATA power cable connects to your hard drives or SSDs.

Efficiency Rating


The maximum efficiency that your power supply can reach depends on how much load it pulls from the wall outlet relative to its wattage. A group called the Ecos Consulting created a rating system called 80PLUS that will tell how efficient your PSU is. As the name suggests, they give badges to PSUs that reach at least 80% efficiency. That means if your power supply is rated at 1000W, it should still not budge even as it draws about 800W from the electrical outlet.

They give out efficiency badges that are inspired by precious metals. A higher rating means there is less wasted energy drawn from the outlet. Here they are with the lowest on top:

  • 82% – Bronze
  • 85% – Silver
  • 87% – Gold
  • 90% – Platinum
  • 92% – Titanium


The PSU’s main job is to distribute power across all your components. You have to know how much each would contribute to the system’s overall power draw. The most power-hungry components are the CPU and the graphics card. It would be wise if you start your computations with these two parts. Generally speaking, a whole system anchored by a top-end CPU and a single graphics card would draw about 300W to 400W on full load, so you would be fine getting yourself a 550W or 660W PSU.

If you plan to build your own PC, do not skimp on the power supply unit. You want all your components connected to a quality PSU. Otherwise, you are at risk of damaging them. It’s better to spend a bit more if it means that your PC will live longer.

Scroll to Top