This part of a PC is often overlooked, do you know what it is?

The power supply is never the most glamourous component in a computer, but it's undeniably important – after all, your PC won't do much if there's no way for electricity to get to the components.

Power supplies sit quietly in the bottom of cases and extend their cables to every part of the rig, delivering electricity to the motherboard, graphics card, hard disk and more.

Cheap PSUs are obviously tempting, but they're usually a bad idea for several reasons – so we've explored what you should look out for when picking a PSU, and picked out some of our favourites from the huge range we have available.

Anatomy of a PSU:

Power supplies are complex bits of kit. A plug delves into one side of the unit, delivering AC electricity, and the PSU filters the electricity, converts it to a DC current, cleans it up a little more and then converts it to run on a primary 12V line and a secondary 5V line. The main line is then divided up for the PC’s components to use at the appropriate voltages, while the second line is used to boot the PC from cold.

Every power supply will have the same set of basic cables. The largest one has pins that deliver most of the power to the motherboard, and there’s a four- and eight-pin connector that plugs in near the processor to deliver extra oomph to the CPU. There will always be one or two cables with connectors for hard disks, SSDs and fans, and there will be at least one cable with two eight-pin connectors for PCI graphics cards.

cables

Get beyond the basics, though, and PSUs become more varied. Some will have more of those PCI plugs to support two, three or even four graphics cards, and others will have more connectors for storage. Most affordable PSUs have a set selection of cables, but some are modular – so you can just use the cables you need, which means that the rest won’t be left to languish around your PC, cluttering up the case and making it look ugly.

There are different PSU form factors, too. The most common is ATX, which will fit almost every PC case, and more powerful units are also available with longer, bulkier designs – great for monster PCs, but make sure that you’ve got a big enough case.

It’s also possible to get small form factor power supplies for tiny mini-ITX and micro-ATX machines, and passive PSUs have no fans – perfect for building silent PCs.

Watts the Problem?

There’s one attribute that matters in a PSU above all others: Wattage. If a power supply is rated to deliver a larger number of Watts, then it’ll be able to support more hardware – and better, more powerful components. It’s as simple as that.

Basic power supplies run between 300W and 500W, and they have limitations about the sort of hardware they support. At the low end of that scale a power supply will only support a PC with a modest processor and an integrated graphics chip – a system fine for basic computing tasks but not much else. Head towards 550W and you can upgrade to a mid-range PSU and a modest graphics card, but that’s it.

You’ll need a PSU like the £83.99 XFX XTR series to build a high-quality gaming rig. Its 550W rating is enough for a decent PSU and a solid graphics card, and its 80 PLUS Gold rating ensures top-notch performance. It’s a modular supply, too, so you can pick your cables – and avoid having any unsightly wires trailing around your case.

If that’s a little pricey, look to the Cougar VTX 650W, which delivers more Wattage for £52.99. It’s not modular, but it has a solid 80 PLUS Bronze rating alongside the power for most gaming rigs. And, if you’re after a more subtle 650W unit, then BitFenix has you covered with its Whisper M – this 80 PLUS Gold box is designed for near-silent operation, and it’s modular too – so it’s a bargain at £84.95.

bitfenix5874abd5b1257

Jumping to a higher Watt rating allows far more versatility. The next category includes PSUs with around 800W of power, and these muscular units will support stonking hardware: they’ll run Core i7 processors and the market’s beefiest graphics cards with no problem, and they also support overclocking.

A unit like the Super Flower Leadex II 850W is a good option: ample power for high-end gaming rigs alongside modular design and an 80 PLUS Gold rating for £129.95.

The growth of efficient components means that there’s less room in the market for monster PSUs – but there are still some occasions when you’ve got to go past 800W. Machines with high-end Intel Core i7 Extreme processors would benefit from a PSU like this, and systems with two or three high-end graphics cards will definitely need to head past 800W – and, perhaps, beyond 1000W.

If you need a PSU at this level, then be prepared to spend some serious dough. A beast like the be quiet! Dark Power Pro P11 delivers a mighty 1,000W of electricity with near-silent performance, a semi-modular design and an 80 PLUS Platinum rating – but it’ll cost you £219.95.

And then, at the top of the market, there’s Ian “8 Pack” Parry – Overclockers UK’s own resident world-record overclocker. He’s worked with Super Flower to deliver the monstrous Leadex Platinum 8 Pack Edition, which serves up 2,000W of power inside a modular, 80 PLUS Platinum design. It costs a huge £379.99, and it’s perfect if you want to build extreme systems with multiple GPUs and groundbreaking tweaks.

8pack5874abd48c231

X-Rated:

The Wattage is the most important factor in a PSU – but its rating and certification is a close second. It’s crucial to pay attention to your PSU’s rating, because better efficiency means better performance – and improved safety.

Power supplies are rated using a system called 80 PLUS. It’s a voluntary programme that measures the efficiency of power supplies, which is a big deal – if a PSU is more efficient it’ll save electricity, reduce heat output and reduce electricity usage.

The lowest 80 PLUS rating requires a PSU to have a flat efficiency rating of 82% at 100% load on its 230V test, and every ranking above that demands more from the power supply – the Bronze rating requires 85%, the Silver needs 87%, and the Gold demands 89%. The best ratings are 80 PLUS Platinum and Titanium, at 90% and 94% respectively – but these are rarer, and PSUs with those ratings are more expensive.

It’s a good rule to buy the best rating that you can afford, but it’s not the only bit of certification that’s worth attention. The other key bit of legislation comes from the EU, and it’s called 617/2013. It’s not particularly exciting, but it means that every power supply in Europe must meet basic 80 PLUS standard on its 230V test.

It’s a big move that should guarantee the efficiency and safety of every power supply on sale, but it’s not that simple. Many cheap power supplies don’t have any 80 PLUS certification at all – so they’re loud, hot, inefficient and unsafe – and many companies list their PSUs as being certified when they’re anything but.

There’s a lot of confusion here, but there’s one simple rule to follow: if it’s too good to be true, it probably is. And if a cheap PSU fails then it doesn’t just break – it’s likely to take the rest of your components with it. That affordable box might seem a bargain at the time, but it could end up costing you hundreds.

Thankfully, dodgy power supplies and absent certifications aren’t anything to worry about if you’re shopping with Overclockers UK. We’ll never sell uncertified power supplies, which means you’re guaranteed a certain level of quality.

Buying a certified PSU doesn’t have to break the bank, either: our favourite budget brand is Kolink, which delivers high-quality units at incredible prices. Take the £35.99 Kolink Core 700W: it’s got enough power for most high-end rigs inside a box with 80 PLUS certification and four PCI Express connectors. You only have to pay five pounds more for something more refined, too – the Kolink KL-SFX450 is a 450W unit with 80 PLUS Bronze certification and the smaller SFX form factor.

cheappsus

Feel the Power:

Every PC needs a PSU, but there’s a lot more to it than just picking up a cheap box and slotting it into your case. Buying from Overclockers UK means you’re always going to get a power supply with the proper certification, and our range stretches from modest, low-Wattage boxes to monster designs for the most ambitious rigs. 

 
 
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