These are the best power supply units you can buy for your PC in 2021

The power supply unit (PSU) plays an incredibly important role inside any desktop PC. It’s responsible for taking alternating current (AC) electricity from the connected power outlet, converting it to direct current (DC), and cleaning it up for better system stability. All computer parts support DC, which is what makes the power supply so important since it provides power to all parts.

What is the best power supply?

It’s paramount we get the power supply right when building or upgrading a PC. They’re rated for a specific output measured in watts, which is the primary metric used in determining which one to choose. A modern processor can draw 200W on its own, and the best graphics cards can draw 400W. Those two components alone would send a 600W power supply to 100% load.

Then there are other components connected to the PSU, including the motherboard. It’s recommended to set aside 100W for this component. Finally, you’ve got drives, expansion cards, lighting, and all accessories connected to USB ports that all require power. We’ll go into a little more detail on how to calculate how much capacity you’ll need.

Unlike other components, we do not recommend saving too much money on the power supply. Because it’s responsible for providing safe, reliable power to all your components, you may find yourself in a position where you’ll need to replace a part or two should your power supply fail or not provide adequate protection.

So long as you choose a reliable brand and spend at least $50, you’ll be able to pick up a PSU that’ll last many years to come. Finally, there’s the PC case that may only support the smaller PSU form factor of SFX instead of the larger ATX. The specification sheet for the chassis should confirm what form factor is supported.

We’ve compiled a list of our favorite power supplies to help you pick the right one.

Best budget power supply: Corsair CX450

Source: Corsair

We’re starting our collection of power supplies with the most affordable PSU we’ll include. The Corsair CX450 is one of the most affordable power supplies we’d actually recommend and it’s from a reputable PC brand. The manufacturer of the power supply can be either Channel Well Technology (RPS0053) or Great Wall (RPS0063), both of which produce many white label units and their own branded PSUs.

450W may sound like not a lot of capacity to work with and you’d be correct there, but for anyone looking to build an office or low-end gaming PC, it’ll have more than enough power to work with. It’s not the most efficient unit either, rocking an 80 Plus Bronze certification, but you shouldn’t expect anything more at this price point.

Being such an affordable power supply, Corsair and its manufacturing partners had to cut corners, and not being modular is one such major omission. This means all cables are tied to the PSU and cannot be removed, so if you don’t have any SATA or Molex devices to hook up to the power supply, you’ll need to stash the cables away inside the PC chassis.

Corsair does include a decent 140mm blower to keep the PSU cool under operation. There’s a single PCIe connection, which illustrates just how basic this power supply is. You could technically locate even more affordable power supplies from the likes of EVGA and Thermaltake, but this PSU from Corsair is where we’d start.

Source: Corsair

Corsair CX450 PSU

We’re biog fans of the affordable, yet reliable Corsair XC450. It has everything you would require for a low-power office or gaming PC. It’s a surprisingly good PSU for the price.

Best 550W power supply: Corsair RM550x

Source: Corsair

Moving up 100W we reach a capacity of 550W from our budget option PSU. This capacity is solid for most PCs with previous generation GPUs that are capable of handling games at 1080p. Just like the 450W Corsair unit, you won’t have much headroom for adding more powerful components at a later date or overclocking and increasing power draw.

We’ve selected the Corsair RM550x as our 550W recommendation, being a slightly more affordable version of its RMi counterpart. All you’re losing here is the digital interface circuit and fans with fluid-dynamic bearings (lower noise and longer lifespan). On the plus side (no pun intended), we have an 80 Plus Gold certificate for efficiency, a considerable ste up from the 80 Plus White.

It’s also fully modular, allowing you to only attach cabling to the PSU you actually plan on using. The 140mm magnetic levitation fan has a zero RPM mode for the system at idle and/or lower loads though you’ll be hard-pressed to hear it at higher loads when used inside a chassis with plenty of case fans.

The Corsair RM550x may be a more budget-friendly PSU, but the brand opted for high-quality internal components, which is great for those who want reliable power delivered to their PC hardware. Inside the box, you’ll see the single 24-pin ATX cable, two 4+4-pin EPS12V cables, as well as a single 6+2 PCIe cable with two connectors.

This power supply offers solid performance, thanks to the numerous features available. Even the Corsair “Type 4” cabling have in-line capacitors on the ATX, EPS, and PCIe cables to further combat any ripples that make it out of the PSU. For the price, this is a solid deal.

Source: Corsair

Corsair RM550x

There’s plenty to appreciate about the Corsair RM550x, including the price and specs. It’s a reliable unit with an 80 Plus Gold efficiency rating. It’s also one of the quietest power supplies in this category.

Best 750W power supply: Cooler Master V750 Gold V2

Source: Cooler Master

750W is now the recommended mid-range for PC builds with many graphics cards, excluding top-tier GPUs, able to draw from such a capacity without overloading the PSU. The CoolerMaster V750 Gold V2 is one of the better choices for 750W power supplies, manufactured by Gospower.

It’s fully modular with a depth of 160mm, fitting inside most PC chassis that support ATX power supplies. A single 140mm fluid dynamic bearing fan is at hand to keep the PSU internals cool under load. A single 24-pin ATX cable, two 4+4-pin EPS12V cables, as well as four 6+2 PCIe cables, are included with the power supply.

This is more than enough for most PC builds and any cables not required can be left inside the box. You may find the distance between peripheral connectors to be a little on the short side, but this is offset with solid performance and set protections for the price. A quality PSU at a reasonable price, makes this our go-to 750W power plant.

Source: Cooler Master

Cooler Master V750 Gold V2

The Cooler Master V750 Gold V2 is a striking power supply, thanks to the available color choice, but it’s also very good at supplying power to your components. An 80 Plus Gold efficiency rating and being fully modular are icing on the sweet cake.

Best 850W power supply: Corsair RM850x

Source: Corsair

This is the second Corsair RMx series power supply featured in our PSU collection. This time we’re moving up the product range to 850W. This is where the latest graphics cards and processors can start to be used together without running out of power. The Corsair RM850x is also one of the best units you can buy from the family of power supplies, so you’re getting good bang for your buck.

As expected at this price point, the PSU is fully modular, allowing you to select and install only the cables required by your PC components. The usual single 24-pin ATX cable comes with three 4+4-pin EPS12V cables, as well as four 6+2 PCIe cables and some SATA connections. The bag of cables is more than enough for most premium PC builds.

Channel Well Technology did a sound job with the construction and build quality of the Corsair RM850x, using premium Japanese capacitors and other high-quality components. This allows the unit to perform reliably under heavier loads, meeting the 80 Plus Gold standard for efficiency.

Source: Corsair

Corsair RM850x

The Corsair RM850x is a reliable PSU for those looking to build a powerful new PC, be it a gaming machine or a video editing workstation. It’s a fully modular PSU with an 80 Plus Gold efficiency rating.

Best 1500W power supply: be quiet! Dark Power Pro 12 1500W

Source: be quiet!

Now this is a power supply you likely do not require, but it would be nice to have access to. The mightily impressive be quiet! Dark Power Pro 12 1500W has a DC output capacity of 1500W. To put this into perspective, that’s three-times the power output of our most budget-friendly PSU in this collection. You likely won’t ever come close to using as much power, but it’s a good choice if you have the money and want one of the best high-capacity plants out there.

Designed for enthusiast use, the Dark Power Pro 12 from be quiet! is also one of the quietest power supplies around thanks to just how much power it’s capable of converting and supplying. We wouldn’t expect anything different from the German PC hardware brand. Its manufacturing partner, Channel Well Technology, also went the extra mile in kitting out this PSU with the best components from its inventory of parts. The majority of the circuits are controlled digitally for tighter and more reliable operation. It’s so efficient, we’re looking at an 80 Plus Titanium certification and be quiet! states the PSU is capable of achieving up to just shy of 95% efficiency.

Even the fan is frameless, allowing be quiet! to draw in more air and lower noise should the PSU need some additional active cooling at higher loads. And it’s possible to control the fan curve digitally, something not many power supplies offer. A major drawback to this PSU, however, is its size. This is understandable due to how much power can be handled by the Dark Power Pro 12, but you may struggle to fit it inside your PC chassis.

For cabling, a single 24-pin ATX cable is included with two 4+4-pin EPS12V cables and ten 6+2 PCIe connections. You’ll struggle to locate PC components that this PSU cannot supply power to. Just be prepared to pay a small fortune for the luxury of owning one of these.

Source: be quiet!

be qiuet! Dark Power Pro

The be quiet! Dark Power Pro 12 is one of the most powerful, high-capacity PSUs you can buy on the market. It’s also a highly power-efficient power supply unit and can handle the load very well.

Best power supply above 1500W: Corsair AX1600i

Source: Corsair

And if 1500W just isn’t enough, why not check out the mighty Corsair AX1600i. It’s rated as one of the best power supplies available right now, thanks to its performance and efficiency. Just like the be quiet! Dark Power Pro 12, Corsair managed to sail through testing with an 80 Plus Titanium rating. Corsair is very serious about the AX1600i and asked its manufacturing partner Flextronics to pack it with just about everything.

As such, the AX1600i is equipped with Gallium Nitride (GaN) MOSFETs and a few other premium internal components that make it a better offering, even against other heavy hitting PSUs in this segment of the market. And just like the Dark Power Pro 12, it’s digitally controlled and you’ll be switching to C19 power cables here instead of C13 to help deal with the additional amperage flowing into the PSU itself.

The Corsair AX1600i is fully modular and comes with a single 24-pin ATX cable, two 4+4-pin EPS12V cables and ten 6+2 PCIe connections. It’s very likely you’ll be connectivity numerous components to this thing since it’s capable of pumping out so much power. Let’s go back to those GaN MOSFETs since they make this more efficient than other PSUs while keeping weight and dimensions of the PSU in check.

It’s only really suitable for enthusiasts who will be drawing more than 1000W of power. But should you have the available budget to cover the cost of the Corsair AX1600i, it’s one of the best power supplies you can buy.

Source: Corsair

Corsair AX1600i

The Corsair AX1600i is one of the most powerful PSUs on the market right now with a humungous power output capacity of 1600W, which is more than you’ll ever need. The highlight of this PSU, however, is its power efficiency.

Best small form factor (SFX) power supply: Seasonic Focus SPX-750

Source: Seasonic

When you’re using a smaller PC case, you’re likely going to be restricted by support for more compact power supplies. An ATX power supply may not fit, which is where SFX PSUs come into play. They can support high capacities and offer excellent efficiency and reliability, but can prove to be vastly more expensive than ATX counterparts.

Seasonic is one of the most reputable manufacturers for power supplies and its own branded range of PSUs are great for PC builds. We’ve chosen the Seasonic Focus SPX-750 as our go-to pick for SFX power supplies, offering a capacity of 750W. We believe this to be the sweet spot for SFF PC builds where the most powerful processors and graphics cards may not be used.

This Seasonic power supply has an 80 Plus Platinum rating for efficiency. All cables are individually sleeved for a premium finish and while this may be a more compact power supply, Seasonic includes a single 24-pin ATX cable, two 4+4-pin EPS12V cables and three 6+2 PCIe cables. You could easily hook up a powerful AMD or NVIDIA GPU without issue.

Source: Seasonic

Seasonic Focus SPX-750

The Seasonic Focus SPX-750 is a brilliant SFX power supply for smaller PC builds. It has an 80 Plus Platinum rating and is capable of delivering up to 750W of clean and reliable DC power.

Choosing the best power supply

Picking the best power supply should factor in your budget (as with any purchase), what components you have or plan on buying, how much capacity is needed, what type of PSU is supported by your chassis (ATX or SFX), and what features are supported. So long as you have a decent 80 Plus rating, all the necessary protections in place, and enough capacity, you should be fine with a reliable brand.

We wouldn’t spend any less than the Corsair CX450. 450W should be considered the bare minimum for a PC with a dedicated GPU and modern processor. This PSU is ideal for office use and light gaming, but you’ll struggle to do much else. Moving up the capacity scale, we have recommendations for 550W, 750W, and 850W.

850W is recommended by NVIDIA and AMD for their top-performing graphics cards, though the mighty RTX 4090 will require something with slightly more as that card alone is capable of drawing 400W. The Corsair RM850x would do just fine in most PC builds. If you have the available budget, be quiet!’s Dark Power Pro 12 has a monstrous 1500W capacity, an 80 Plus Titanium rating for efficiency and has high-end components that are mostly digitally controlled.

And for those who have more compact cases, we’d go for the Seasonic Focus SPX-750. It’s compact, powerful, and has some premium features, though you’ll be paying more than an ATX equivalent.

ATX vs. SFX: What’s the difference?

There’s not much to separate the ATX and SFX form factors aside from dimensions of the power supply. ATX is the standard size and is supported by most PC cases. SFX (and SFX-L) are also supported across the board, but have the bonus of being small enough to fit inside more compact cases.

• ATX: 150 x 140 x 86
• SFX-L: 125 x 125 x 64
• SFX: 125 x 100 x 63.5

How much power capacity do I need?

It’s straightforward to work out just how much capacity you require by looking at the specifications of your CPU and GPU. Generally speaking, you’ll want to factor in both power draw figures and add an additional 100W – 150W to cover the motherboard and all other hardware inside (and connected to) the PC — things like the best PC monitors don’t count as they supply their own power.

The Intel Core i9-13900K is capable of pulling 250W of power. The NVIDIA GeForce RTX 4090 is capable of pulling 500W of power. Adding both together with a conservative estimate for the rest of the system gives us: 500W + 250W + 150W = 900W. Therefore, a 900W or higher power supply would be ideally suited for our system.