Power supply

There are a lot of components to consider in your PC. So what size power supply should you get to provide juice for them all?

Building a PC is exciting, as is choosing the components you're going to install. But it all begins with the power supply. If you don't have enough power running through the system, you can forget about that fancy processor or monster graphics card.

Our complete PC build guide can help you on your way with choosing and installing components, but once you know what you want in your system it's important to make sure you have a power supply that's sufficient to make everything work.

Don't just go for the biggest

Enormous power supplies for most PC builds aren't necessary. Sure, you might like to say you have a 1,200W power supply unit (PSU) in your system, but unless you're using multiple GPUs, crazy high-end CPUs, or doing a whole lot of overclocking, it's just overkill.

Your system won't be running at maximum all the time. If it idles at 80W, say, it'll idle at 80W whether you have a 600W PSU or a 1200W PSU so long as they're as efficient as each other. The higher values provide more headroom for more stressful scenarios.

How much do you actually need?

There are tools online that can help you quickly figure out which power supply to get. Some are pretty basic, others less so. I used EVGA's Power Meter when choosing my power supply, though as a manufacturer the company also uses it to recommend products from its range. But it does the trick. It asks you some basic questions on how many drives you have, what type, what your CPU is, your GPU and if you're overclocking.

A good alternative is vbutils. This goes a little more in-depth on the components you're using, and will recommend a base value and to go a percentage over. Giving yourself a little headroom for future expansion is smart. Giving yourself 600W of headroom is still overkill.

Checking your connectors

Besides the actual power rating, you also need to make sure that the PSU you choose can provide the right connectors to hook up all your parts. Generally, we recommend a modular power supply because you only ever have to attach the cables you're going to need. It's easier to deal with and neater inside your PC.

A couple of key areas to check are SATA connections and GPU connections. If you don't have enough SATA power connections for the number of drives you have now, or may have in the future, you're already finding a fault. There are ways around this, like Molex to SATA adapters, but that's less ideal.

The same can be said of the GPU. While you may only use a single six-pin or eight-pin connector right now, what about if you upgrade? Again, see what you currently require power for, and try and leave a little headroom.

Quality and size

There is a rating system for power supplies known as 80 Plus. This rates how well a unit keeps up at 80 percent efficiency over its load range and is measured in five stages.

As a rule of thumb, higher 80 Plus ratings are more efficient power supplies and overall better quality. They'll also be more expensive. The best balance you need to make is to get the best 80 Plus rating you can afford in your build.

You also need to consider the actual physical size of the PSU you're putting into your PC. In a huge tower-style case it might not matter, but even then, make sure you're not blocking any drive bays by getting a gargantuan power supply you may not need. There are lots of great options that are also very small.

That covers off the basics, but if you have any tips of your own to share drop them into the comments.

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