A PC that requires an 850-watt power supply is serious business. Once you hit this level of performance (and power consumption), you need a reliable and high-quality power supply that matches the rest of your components. But that’s easier said than done, as picking out the best 850 W PSU amongst all the contenders can be challenging. Thankfully, that’s where we come in.

Our list of the best 850 W power supplies focuses on high-quality units with proven electrical performance. These boast 80 Plus Gold efficiency at a minimum, with nice-to-have features like fluid dynamic bearing (FDB) fans and modular connectivity as standard. With that in mind, read on to see what made the cut.

Our Picks for the Best 850 W Power Supplies

1. Corsair RM850x (2021)

Corsair’s RM850x has always been one of the best power supplies out there. The company’s 2021 refresh keeps it at the top of the pack, with improved electrical performance and a new higher-quality fan. Corsair hasn’t rested on its laurels, and these improvements help the RM850x stand out in a crowded market segment.

Load regulation on the crucial 12-volt rail is excellent, with the RM850x keeping deviation below 1%. It’s an impressive performance that puts the RM850x in the upper echelons of 850-watt power supplies.

Ripple suppression is even more remarkable. It moves into the lead here in Tom’s Hardware’s tests, besting all its competitors with an impressive 8.24 mV ripple on the 12-volt rail. It’s better than the already-impressive 2018 model in both tests, which is what you’d hope for from an updated unit. The improvement isn’t significant enough to justify upgrading from the 2018 to the 2021 model, but it’s still great to see.

The 2021 RM850x boasts great build quality and excellent components, as you may expect given the great electrical performance. You get a durable (and quiet) magnetic levitation fan, high-quality soldering, and 100% Japanese capacitors. Corsair’s also ensured that there’s decent space between components for better airflow and cooling.

Corsair hasn’t just improved the internal components, either. The 2021 RM850x comes with a new and, in our opinion, superior case that boasts triangular mesh cutouts. It’s a small touch, but we think it adds welcome visual flair to an otherwise functional component.

To top it all off, Corsair backs its 2021 RM850x with a 10-year warranty, as you’d hope for with such a high-wattage power supply. Combine that with the competitive price, good components, and excellent electrical performance, and you get a fantastic choice for the best 850 W power supply.

2. XPG Core Reactor 850

XPG isn’t the most well-known name in power supplies, but its Core Reactor 850 shows that it can hang with the big boys. Good electricals combined with impressive efficiency and an extra-compatible 140 mm length make it a strong alternative candidate to familiar names.

The XPG’s load regulation on the 12-volt rail is good, if not the best. It can’t offer the ruler-flat line of some competitors in TechPowerUp’s testing, but it’s still well within safe limits. The 12-volt rail never surpasses 2% deviation regardless of load level, so there’s nothing to worry about here.

TechPowerUp’s ripple suppression table shows more good news. The Core Reactor 850 keeps ripple well under control, posting excellent results that rival the best. Twelve-volt ripple is under 20% of the 120 mV limit throughout the testing, with only the 3.3-volt rail creeping past 50% of the 50 mV limit here. But that only happens at 100% and 110% load, which you shouldn’t ever reach in daily use. Beyond that, we’re well below 50% ripple on all the minor rails.

XPG’s 850-watt power supply also comes with high-quality components, such as a fluid dynamic bearing (FDB) fan. This helps keep noise levels low, with the Core Reactor 850’s average noise output coming in at just under the 27 dBA mark. The XPG Core Reactor also has 100% Japanese capacitors and boasts 92% average efficiency, which means it meets the new ATX 3.0 spec.

One area where XPG stumbles slightly is the included cables. The company ships the Core Reactor 850 with sleeved ATX, EPS, and PCIe cables, which aren’t as easy to cable-manage as flat, ribbon-style cables.

The XPG may not be a class leader on all fronts, but its lower noise, 140 mm length, and ATX 3.0 compatibility make it an appealing choice if you value one (or all) of these factors. Add to it a solid 10-year warranty, and you have a great alternative for the best 850 W power supply units on the market.

3. Asus ROG Thor 850 W

Asus’ ROG Thor assuredly demonstrates that you can have form and function in one package. Its exquisite looks may catch the eye first, but its low noise and excellent electricals mean that the Thor has substance to back up its shiny exterior.

Its electrical credentials are commendable. KitGuru’s testing shows strong load regulation capabilities, keeping deviation under 1% regardless of the rail or load applied to the power supply. It also manages to stay near-perfect at full load, which isn’t something most power supplies can claim.

Ripple suppression is similarly strong, not even getting halfway close to the 120 mV limit present in the ATX power supply specifications. Although Asus may be a relatively new player in the power supply game, the ROG Thor 850 W shows that they can compete with the established names in these crucial areas.

The ROG Thor 850 W’s efficiency is solid, too. It achieves 94% efficiency at about 50% load, easily earning its Platinum efficiency rating.

Beyond the solid electrical performance, Thor’s standout feature must be its aesthetics. It has an OLED screen that shows a real-time readout of your computer’s power draw. It’s perhaps not as practical as you may think, but it’s great for a showcase build in a tempered glass case. Asus bolsters the OLED with RGB lighting and RGB Aura Sync support, perfect for an Asus-heavy build.

If all of that wasn’t tempting enough, the Thor’s noise levels are also impressive. Its Asus-patented double ball-bearing (DBB) fan runs quietly, only becoming noticeable at around 675 watts load. Even then, it only hits around 31 dBA, which is still acceptable for a power supply.

Asus tops all of this off with a 10-year warranty, which is the minimum we expect for this price and power level. Overall, the Asus ROG Thor 850 W’s unique visuals, electrical performance, low-noise operation, and Platinum efficiency make this the go-to 850 W power supply if you’re looking to make a statement.

4. Thermaltake Toughpower GF3 850 W

Thermaltake’s Toughpower GF3 850 W stands out as one of the best ATX 3.0 compatible power supplies in this power bracket, perfect for those seeking to adopt the newer standard. But that’s not the only trick up its sleeve: you’ll get safe performance, a good and quiet-running fan, and a well-built unit should you opt for this 850-watt power supply.

Although it’s not quite on par with our top two power supplies, the Thermaltake’s electrical performance is well within safe limits. Tom’s Hardware’s testing shows just over 1% deviation on the 12-volt rail, which is perfectly acceptable.

There’s nothing out of place to note in the ripple suppression result, either. Just under 19 mV of ripple on the 12-volt rail is great, considering that the ATX spec allows for 120 mV. It still trails the very best 850 W power supplies, but it’s broadly fine and nothing at all to worry about.

The GF3’s main selling point is its ATX 3.0 compliance. At the time of writing, it’s only one of a handful of 850-watt units that meets these latest standards. It may not seem all that relevant now, but the GF3 is a good choice if you want a somewhat future-proof power supply. The GF3’s 10-year warranty helps here, ensuring that you’ll be able to use it for a long time without having to replace it.

Like many high-quality power supplies, the Toughpower GF3 has a fluid dynamic bearing (FDB) fan on board. FDB fans are known for lower noise and better longevity, which is the case here. The GF3 will remain quiet under load, only breaking past the 30 dBA mark once you get close to its maximum 850-watt capacity.

One small touch we appreciate is the GF3’s flexible ribbon-style power cables. You will have to deal with a sleeved ATX cable, but the rest are easy to live with and perfect for cable management in any modern PC case.

The Thermaltake Toughpower GF3 850 W isn’t the best 850 W power supply you’ll ever find. However, its good build quality, quiet fan, and solid electrical performance, combined with full ATX 3.0 compatibility, make it a strong contender if you want to be on the cutting edge of power supply unit standards.

5. Lian-Li SP850

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Small form factor (SFF) rigs usually don’t need a ton of power, but there are always exceptional builds that squeeze in high-end components into tiny cases. Lian Li’s SP850 is a power supply for those builds. This is the power supply to go for if you need high power output and excellent electrical performance in a tiny package.

The Lian Li proves that size doesn’t matter, at least as far as power supplies go. Load regulation is superb across all of its power rails, with less than 1% deviation on the most important rails.

It’s also good news on the ripple suppression front. Testing shows that the SP850 doesn’t exceed 23 mV on any rails, regardless of load. That’s particularly impressive on the 12-volt rail, which has a ripple limit of 120 mV.

This level of performance isn’t a surprise if you look at the internal components. Teardowns show good quality soldering and 100% Japanese caps, all hallmarks of the best power supplies. You also get a fluid dynamic bearing fan, which helps the SP850 remain quiet under load.

Lian-Li ships the SP850 with a 12-pin PCIe 5.0 cable, so you can power Nvidia RTX 40-series cards without any adapters. You probably won’t fit an RTX 4090 in an SFF case, but this is a good addition for the lower-power 40-series cards that will come out eventually.

All of the SP850’s cables are braided, but they’re free of in-cable capacitors. This is a great feature, as it makes the cables more flexible and easier to route. It’s a crucial feature for cable management in a cramped SFF case.

The Lian-Li SP850 is ideal for those who need a lot of power without jumping ship to an ATX-sized power supply or case. We wish it had a longer warranty, but short five-year warranties seem quite standard for an SFX power supply Besides, the SP850 does so well elsewhere that the shooter warranty is worth the trade-off in our books.

The Lian-Li SP850 is also available in white.

Closing Thoughts

High-end rigs require high-end power, and that’s precisely what the best 850 W power supplies deliver. Any of these power supplies will provide enough juice for high-power components, all while operating safely and dependably.

Corsair’s RM850x power supply will deliver the goods for most users who want that best-in-class electrical performance at a reasonable price. XPG’s Core Reactor 850 is another strong contender, offering strong electrical performance and ATX 3.0 compatibility at a competitive price.