Buying Guide
The Best 850W Power Supplies for a Single-GPU Gaming PC
We compared five ATX 3.1 units on the details that decide whether one suits your build: PCIe connectors, depth, measured noise and warranty.
By The PC Journal editorial team
10 min read5 products evaluated
Most 850W power supplies can run a single graphics card and a mainstream CPU. What separates them is less obvious: how many PCIe cables they ship with, whether two connectors share one cable, how deep the unit is, and how loud it gets under a gaming load.
All five picks here support ATX 3.1 and include a native 12V-2x6 cable for current graphics cards. We compared them on published specifications, the cable lists in Hardware Busters' reviews, and Cybenetics noise and efficiency measurements at 115V. We did not test these units ourselves.
One check applies to every pick: count the power sockets on your exact graphics card before you choose. A unit with plenty of wattage but too few PCIe connectors still needs an adapter.
Quick Picks
Our 5 recommendations at a glance. Tap a pick for the full verdict.
Quietest Measured
be quiet! Pure Power 13 M 850W
The quietest Cybenetics result of the five, with four PCIe 6+2 connectors.
Best for: Quiet builds, and graphics cards that still use three or four 8-pin connectors.
Our take Check price for be quiet! Pure Power 13 M 850W (opens in a new tab)
Best for Short PSU Bays
Seasonic Focus GX-850 (ATX 3.1)
A 140mm unit with Platinum efficiency and three separate PCIe cables.
Best for: Compact ATX and micro-ATX cases with little room behind the PSU.
Our take Check price for Seasonic Focus GX-850 (ATX 3.1) (opens in a new tab)
Best Value Short Unit
Corsair RM850e (2025, ATX 3.1)
A short, quiet Gold unit that covers most single-GPU builds.
Best for: Short PSU bays where you want lower noise than the Seasonic.
Our take Check price for Corsair RM850e (2025, ATX 3.1) (opens in a new tab)
Best for 12V-2x6 Cards
MSI MAG A850GLS PCIE5
Quiet and Platinum-rated, but with only two PCIe 6+2 connectors.
Best for: Graphics cards that use one 12V-2x6 connector.
Our take Check price for MSI MAG A850GLS PCIE5 (opens in a new tab)
Best for Three-Socket Cards
Corsair RM850x (ATX 3.1)
Three separate PCIe cables, a 140mm fan and a 10-year warranty.
Best for: Mid-tower cases with room behind the PSU and a three-socket graphics card.
Our take Check price for Corsair RM850x (ATX 3.1) (opens in a new tab)
| Pick | Why it’s here | Best for | Price |
|---|---|---|---|
| The quietest Cybenetics result of the five, with four PCIe 6+2 connectors. | Quiet builds, and graphics cards that still use three or four 8-pin connectors. | Check price for be quiet! Pure Power 13 M 850W (opens in a new tab) |
| A 140mm unit with Platinum efficiency and three separate PCIe cables. | Compact ATX and micro-ATX cases with little room behind the PSU. | Check price for Seasonic Focus GX-850 (ATX 3.1) (opens in a new tab) |
| A short, quiet Gold unit that covers most single-GPU builds. | Short PSU bays where you want lower noise than the Seasonic. | Check price for Corsair RM850e (2025, ATX 3.1) (opens in a new tab) |
| Quiet and Platinum-rated, but with only two PCIe 6+2 connectors. | Graphics cards that use one 12V-2x6 connector. | Check price for MSI MAG A850GLS PCIE5 (opens in a new tab) |
| Three separate PCIe cables, a 140mm fan and a 10-year warranty. | Mid-tower cases with room behind the PSU and a three-socket graphics card. | Check price for Corsair RM850x (ATX 3.1) (opens in a new tab) |
Our Picks
Quietest Measured1 of 5
be quiet! Pure Power 13 M 850W on Amazon (opens in a new tab)
The Pure Power 13 M is the pick when fan noise matters most: Cybenetics rated it A++ at an average of 10.65 dB[A], the quietest result in this comparison.
Best for
- Quiet builds, and graphics cards that still use three or four 8-pin connectors.
Skip if
- Your case limits PSU length to about 150mm, or drive cages or fans sit behind the PSU.
Why we like it
It also has the most flexible cable set here, with four PCIe 6+2 connectors across three cables plus a native 12V-2x6, so it can power older three-socket cards and current 12V-2x6 cards alike. The fan stops completely at low load, and Cybenetics rated its efficiency Platinum (90.834% average at 115V).
The trade-off is size. At 160mm deep it is one of the two longest units here, which matters in compact cases or when a bottom fan sits behind the PSU.
Key dimensions & specs
- Depth: 160mm
- PCIe 6+2: 4 connectors on 3 cables
- 12V-2x6: 1 native cable
- Cybenetics: Platinum, A++ (10.65 dB[A])
- Warranty: 10 years
Pros
- Quietest noise result here
- Four PCIe 6+2 connectors
- Fan stops at low load
- 10-year warranty
Cons
- 160mm deep
- Rifle-bearing fan, not fluid dynamic
Best for Short PSU Bays2 of 5
Seasonic Focus GX-850 (ATX 3.1) on Amazon (opens in a new tab)
The Focus GX-850 V4 is the pick when space behind the PSU is tight: it is 140mm deep, has three separate PCIe cables, and carries a 10-year warranty.
Best for
- Compact ATX and micro-ATX cases with little room behind the PSU.
Skip if
- You want the quietest system possible; the be quiet! and MSI measured lower noise.
Why we like it
Seasonic builds it in-house with a 135mm fluid dynamic bearing fan, and Cybenetics rated it Platinum for efficiency. Three separate PCIe cables mean a three-socket graphics card never has to share a cable. Its noise rating is the weakest of the five (Cybenetics A-, 25 to 30 dB[A]), so the Corsair RM850e is the better short option if quiet matters more than efficiency.
Key dimensions & specs
- Depth: 140mm
- PCIe 6+2: 3 connectors on 3 cables
- Fan: 135mm fluid dynamic bearing
- Cybenetics: Platinum, A- (25 to 30 dB[A])
- Warranty: 10 years
Pros
- 140mm deep
- Three separate PCIe cables
- Platinum efficiency
- 10-year warranty
Cons
- Highest noise rating here
- Older ATX 3.0 units share the name
Best Value Short Unit3 of 5
Corsair RM850e (2025, ATX 3.1) on Amazon (opens in a new tab)
The 2025 RM850e matches the Seasonic's 140mm depth with a quieter result: Cybenetics rated it A (20 to 25 dB[A]) and Gold for efficiency.
Best for
- Short PSU bays where you want lower noise than the Seasonic.
Skip if
- Your card needs three separate 8-pin cables, or you want more than a 7-year warranty.
Why we like it
Corsair offers a 120mm rifle-bearing fan with a low-noise fan curve, 105°C-rated capacitors and Modern Standby support. Hardware Busters' cable list shows three PCIe 6+2 connectors on two cables, so two connectors share one cable.
That shared cable is the main thing to check. If your graphics card has three 8-pin sockets and its maker recommends separate cables, the Seasonic or the RM850x is the safer choice.
Key dimensions & specs
- Depth: 140mm
- PCIe 6+2: 3 connectors on 2 cables
- Fan: 120mm rifle bearing
- Cybenetics: Gold, A (20 to 25 dB[A])
- Warranty: 7 years
Pros
- 140mm deep
- Quieter than the Seasonic
- Modern Standby support
- 105°C-rated capacitors
Cons
- Two PCIe connectors share a cable
- Shorter 7-year warranty
Best for 12V-2x6 Cards4 of 5
MSI MAG A850GLS PCIE5 on Amazon (opens in a new tab)
The MAG A850GLS is the pick for a graphics card powered by a single 12V-2x6 connector: it measured Platinum efficiency (89.955%) and A+ noise (18.07 dB[A]) in Cybenetics testing.
Best for
- Graphics cards that use one 12V-2x6 connector.
Skip if
- Your card has three 8-pin sockets; this unit has two PCIe 6+2 connectors.
Why we like it
MSI offers a 150mm length and a 135mm fluid dynamic bearing fan, and the 12V-2x6 cable is a native dual-color design that shows whether it is fully seated. It has only two PCIe 6+2 connectors, though, so it cannot power a three-socket card without an adapter.
Check the model name carefully. The older MAG A850GL PCIE5, without the S, is a different unit that was not Cybenetics-tested when Hardware Busters reviewed it.
Key dimensions & specs
- Length: 150mm
- PCIe 6+2: 2 connectors
- Fan: 135mm fluid dynamic bearing
- Cybenetics: Platinum, A+ (18.07 dB[A])
- Warranty: 10 years
Pros
- Second-quietest result here
- Platinum efficiency
- Fluid-bearing fan
- Dual-color 12V-2x6 cable
Cons
- Only two PCIe 6+2 connectors
- Easily confused with the A850GL
Best for Three-Socket Cards5 of 5
Corsair RM850x (ATX 3.1) on Amazon (opens in a new tab)
The ATX 3.1 RM850x is the pick for a graphics card with three 8-pin sockets and room in the case: it has three separate PCIe cables and a 10-year warranty.
Best for
- Mid-tower cases with room behind the PSU and a three-socket graphics card.
Skip if
- Your case limits PSU length to 150mm or less.
Why we like it
It uses the largest fan here, a 140mm fluid dynamic bearing unit, and Cybenetics rated it Gold for efficiency and A for noise (20 to 25 dB[A]). Corsair's embossed cables and low-profile combs make routing tidier than most.
At 160mm deep it needs the same clearance as the be quiet!, which is quieter and has one more PCIe connector. The RM850x makes sense if you prefer Corsair's cable set or its fan.
Key dimensions & specs
- Depth: 160mm
- PCIe 6+2: 3 connectors on 3 cables
- Fan: 140mm fluid dynamic bearing
- Cybenetics: Gold, A (20 to 25 dB[A])
- Warranty: 10 years
Pros
- Three separate PCIe cables
- Largest fan here
- 10-year warranty
- Easy-to-route cables
Cons
- 160mm deep
- Gold, not Platinum
How We Chose These 850W Power Supplies
Each pick was assessed across 4 criteria weighted for real-world use.
- Connectors
- We counted PCIe 6+2 connectors and cables from Hardware Busters' cable lists, since they decide which graphics cards a unit can power without adapters.
- Physical fit
- We recorded each unit's depth. Across these picks it ranges from 140mm to 160mm, enough to decide fit in compact cases.
- Measured noise
- We used Cybenetics noise ratings at 115V as reported by Hardware Busters, not fan-noise impressions from user comments.
- Efficiency and warranty
- We compared Cybenetics efficiency results and warranty length as secondary factors once fit and connectors were settled.
What to Look for in 850W Power Supplies
Key buying criteria so you get the right fit the first time.
Count connectors before watts
Your graphics card's spec page lists its power sockets: one 12V-2x6, two 8-pin or three 8-pin. A unit needs a matching cable for each socket, and 850W does not help if it has too few connectors.
Check the exact card model, not the GPU name. Partner cards with the same chip often use different sockets.
One cable, two plugs
Some units put two PCIe connectors on one cable. That is common and not a defect, but the Corsair RM850e does it on two of its three connectors.
If you plan to use both plugs on one card, read the graphics card maker's installation guidance first.
Depth and case clearance
Case manuals list a maximum PSU length. Subtract room for the modular plugs, which stick out from the back of the unit, and for any bottom fan or drive cage behind it.
A 140mm unit like the Seasonic or RM850e fits more compact cases than the 160mm be quiet! or RM850x.
12V-2x6 is a socket change
ATX 3.1 replaced the 12VHPWR socket with 12V-2x6, whose shorter sense pins keep power off until the plug is fully seated. The cable itself did not change.
Whichever unit you buy, push the plug in until it clicks and avoid bending the cable right at the connector.
Cybenetics over 80 Plus
80 Plus checks efficiency at a few load points. Cybenetics measures across many load levels and also rates noise, from A++ (quietest) down.
The noise rating is the better guide to how a unit will sound under your desk.
Never mix modular cables
Modular cables share the same plug at the component end, but the pinout at the PSU end differs between brands and even between models of one brand. Corsair's cable compatibility guidance warns against mixing them.
Using a cable from an old unit can damage drives, the motherboard or the graphics card. Use only the cables supplied with your exact PSU.
How to Choose 850W Power Supplies
By priority
| Priority | Consider | Why |
|---|---|---|
| The quietest system | be quiet! Pure Power 13 M 850W | A++ noise rating, the lowest here |
| A 140mm PSU bay | Seasonic Focus GX-850 | 140mm with three separate PCIe cables |
| Short and quiet | Corsair RM850e (2025) | 140mm with an A noise rating |
| A 12V-2x6 graphics card | MSI MAG A850GLS PCIE5 | Platinum and A+, but two PCIe 6+2 |
| A three-socket card with room to spare | Corsair RM850x (ATX 3.1) | Three separate cables, 140mm fan |
Scroll sideways to see every column.
By graphics card power sockets
| Your card has | Units that fit without adapters |
|---|---|
| One 12V-2x6 | All five |
| Two 8-pin | All five |
| Three 8-pin | be quiet!, Seasonic, RM850x (separate cables); RM850e (one shared cable) |
Check the sockets on your exact card model; partner cards with the same GPU can differ.
By price at the time of writing
Prices change often; these tiers reflect Amazon prices when this guide was updated.
| Price tier | Power supplies |
|---|---|
| About $110 to $120 | be quiet! Pure Power 13 M, Corsair RM850e |
| About $140 to $160 | MSI MAG A850GLS, Corsair RM850x, Seasonic Focus GX-850 |
Frequently Asked Questions
Is 850W enough for my graphics card?
For most single-card builds, yes. Check your card maker's recommended PSU wattage for the exact model, and remember that the connector count matters as much as the wattage.
Can I use an adapter instead of a native 12V-2x6 cable?
Every pick here has a native 12V-2x6 cable, so you should not need one. A native cable avoids the extra plug an adapter adds.
Can I reuse the modular cables from my old power supply?
No. Pinouts at the PSU end differ between brands and models, and a mismatched cable can damage components. Use only the cables supplied with the new unit.
Is Platinum efficiency worth paying more for?
Efficiency mainly affects heat and a little power cost. For a quiet build, the Cybenetics noise rating is the more useful number to compare.
How do I check that a PSU fits my case?
Find the maximum PSU length in the case manual, then leave space for the modular plugs and anything mounted behind the PSU. Compare that with the unit's depth.
Does the fan stop at low load?
The be quiet! and Corsair RM850e list a fan that stops or runs slowly at low load. Check the listing for a zero-RPM or hybrid fan mode if silence at idle matters.
Bottom Line
Start with your graphics card's power sockets and your case's PSU clearance. Those two checks narrow five units to one or two. The be quiet! Pure Power 13 M is the quietest and most flexible if you have 160mm of room; the Seasonic Focus GX-850 and Corsair RM850e are the 140mm options, with the Seasonic trading noise for three separate cables.
The MSI MAG A850GLS suits a 12V-2x6 card, and the Corsair RM850x is the alternative for a three-socket card in a roomier case.