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Best Power Supplies 2021

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Best Power Supplies
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Your PC's power supply / PSU plays a big role in determining your system's reliability, depending on its performance. So you should be careful when it comes to picking the right PSU for your system. The best power supply should also have features to save your system's parts (including the power supply itself), in case something goes wrong with your electricity supply or other components. If it doesn't, it's clearly not the best power supply and is putting your other expensive PC parts at risk.

You'll also have different concerns, of course, depending on whether your power supply will be pushing a monster mining rig, an always-churning workstation, or a basic productivity or gaming PC. We’ll help you find the best power supply for your next desktop PC below.

Quick Power Supply Shopping Tips

First, figure out your wattage requirements. You don't need to purchase much more potential power capacity (wattage) than you’ll ever use. You can calculate roughly how much power your new or upgraded system will draw from the wall and look for a capacity point that satisfies your demands. Several power supply sellers have calculators that will give you a rough estimate of your system's power needs. You can find a few below:

You probably don’t need a 1,000-watt PSU, even for an extreme gaming rig. A few years ago, all graphics cards on the high-end of our GPU Benchmarks hierarchy were very power hungry. But this has changed with Nvidia's recent architectures. It's simply not necessary to buy a 1kW PSU for a couple of RTX 2080s. An 800W model will do just fine, leaving headroom for an overclocked best CPUs for gaming as well, as you can see in our CPU Benchmarks hierarchy. Fans of AMD's high-end Radeon VII or the newer Radeon RX 5700 XT will need to plan for higher power use, pairing these cards with PSUs featuring greater maximum output.

Check the physical dimensions of your case before buying. If you have a standard ATX PC case, chances are an ATX power supply will fit. But many higher-wattage PSUs are longer than the typical 5.5 inches. So you’ll want to be sure of your case’s PSU clearance. If you have a particularly tiny or slim PC case, it may require a less-typical (and more compact) SFX power supply. We have picks for this form factor below as well.

For more on this subject, see our A Basic Guide To Motherboard, Case and Power Supply Form Factors feature.

Want a clean build or working in a tiny case? Consider a modular power supply. If your case has lots of room behind the motherboard, or your chassis doesn’t have a window or glass side, you can of course cable-wrap the wires you don’t need and stash them inside your rig. But if the system you’re building doesn’t have space for this, or there’s no easy place to hide your cable mess, it’s worth paying extra for a modular power supply. Modular PSUs let you only plug in the power cables you need and leave the rest in the box.

The Best Power Supplies You Can Buy Today

Corsair CX450 (Image credit: Corsair)

1. Corsair CX450

Best Cheap PSU ($60/£60 or less)

Specifications
Manufacturer (OEM): Channel Well Technology or Great Wall
Max. DC Output: 450W
Efficiency: 80 PLUS Bronze, Cybenetics Bronze (CWT), Cybenetics Silver (GW)
Noise: Cybenetics A- (CWT, 20-25 dBA), Cybenetics Standard+ (GW, 35-40 dBA)
Form Factor: ATX12V v2.4, EPS 2.92
Cooling: 120mm Rifle Bearing Fan (HA1225M12F-Z or D12SM-12 )
Modular: No
Connectors: 1x EPS, 1x PCIe
Warranty: 5 years
Reasons to buy
+Low price+Full set of protection features+Great soldering quality+Rifle bearing fan+Five-year warranty
Reasons to avoid
-Single PCIe connector limits expansion-Not as quiet as the CWT-made CX450-Short distance between peripherals connectors

Of the two variants of Corsair's CX450, the Great Wall version is more efficient than CWT's, especially under light loads, and has a more efficient 5VSB rail. On the other side, it has a more-aggressive fan profile, so its noise output is increased. In the US market, you will only find the CWT version, which is made in Vietnam instead of China, so it avoids the tariffs and keeps its price tag low.

Read: Corsair CX450 Review

Alternate Best Cheap Power Supply: Corsair VS450

Another decent alternative if your budget is low, you need more than 500W of capacity, and you aren't that concerned about efficiency or some fan noise under load is the Corsair VS650. It won't win any performance awards, but it gets the job done without much in the way of frills or fuss, for less than $50. You may also be able to save on these or other PSUs by checking Corsair coupon codes.

Corsair RM550x (2021) (Image credit: Corsair)

2. Corsair RM550x (2021)

Best PSU: Up to 550 Watts

Specifications
Manufacturer (OEM): CWT
Max. DC Output: 550W
Efficiency: 80 PLUS Gold, Cybenetics Gold
Noise: Cybenetics A+ (15-20 dBA)
Form Factor: ATX12V v2.4, EPS 2.92
Cooling: 140mm Magnetic Levitation Fan (NR140ML)
Modular: Yes
Connectors: 1x EPS, 2x PCIe
Warranty: 10 years
Reasons to buy
+High overall performance+Silent operation+Highly efficient at light load+Magnetic Levitation fan+Fully modular+10-year warranty
Reasons to avoid
-In cable capacitors-Single EPS connector-Small distance between peripheral connectors

The smallest member of the new RMx line gets updated with a top-notch magnetic levitation fan which doesn’t affect the overall noise output, so the new RM550x is one of the quietest PSUs in the 550W category. It would be nice if Corsair added a second EPS connector in this unit, but most folks will be more than satisfied with the connection options. 

Read: Corsair RM550x Review

Alternate Best PSU 550W: Phanteks AMP Series 550W

XPG Core Reactor 650W (Image credit: Tom's Hardware)

3. XPG Core Reactor 650W

Best PSU: Up to 650 Watts

Specifications
Manufacturer (OEM): CWT
Max. DC Output: 650W
Efficiency: 80 PLUS Gold, Cybenetics Platinum
Noise: Cybenetics A (20 - 25 dBA)
Form Factor: ATX12V v2.52, EPS 2.92
Cooling: 120mm Fluid Dynamic Bearing Fan (HA1225H12F-Z)
Modular: Fully
Connectors: 2x EPS, 4x PCIe
Warranty: 10 years
Reasons to buy
+Full power at 47 degrees Celsius+High performance+Efficient+Silent operation+Good build quality+Compatible with the alternative sleep mode+Fully modular
Reasons to avoid
-Two EPS connectors on the same cable-The transient response at 3.3V could be better

The XPG Core Reactor with 650W max power can achieve higher overall performance than the two hottest picks in this category, the Corsair RM650x, and the Seasonic Focus Plus Gold, with similar capacity. It also has a silent operation, thanks to the relaxed fan profile, despite its compact dimensions. The build quality is high, and the provided warranty meets the competition's offerings. Finally, the two EPS connectors provide compatibility with the high-end mainboard, but they should be installed on dedicated cables—all in all, an excellent power supply.

Read: XPG Core Reactor 650W PSU Review

Alternate Best PSU 650W: Thermaltake Toughpower PF1 650W

Corsair RM750x (Image credit: Tom's Hardware)

4. Corsair RM750x (2021)

Best PSU: Up to 750 Watts

Specifications
Manufacturer (OEM): CWT
Max. DC Output: 750W
Efficiency: 80 PLUS Gold, Cybenetics Gold
Noise: Cybenetics A- (25 - 30 dBA)
Form Factor: ATX12V v2.4, EPS 2.92
Cooling: 135mm Rifle Bearing Fan (NR135L)
Modular: Fully modular
Connectors: 2x EPS, 4x PCIe
Warranty: 10 years
Reasons to buy
+High overall performance+Silent at low and mid loads+Highly efficient at light loads+Magnetic Levitation fan+Fully modular+10-year warranty
Reasons to avoid
-The fan speed profile could be even more relaxed-In cable capacitors-Small distance between peripheral connectors

It wasn't easy to deliver a better product than the existing RM750x (2018), but Corsair managed to do this, and the new model achieves notably better performance. Compared to the previous model, it loses in quietness, but you cannot call it noisy with 28 dBA overall noise output. All in all, this is an excellent power supply, leading the 750W Gold category. 

Read: Corsair RM750x (2021) PSU Review 

Alternate Best PSU 750W: XPG Core Reactor 750

Corsair RM850x (2021) (Image credit: Tom's Hardware)

5. Corsair RM850x (2021)

Best PSU: Up to 850 Watts

Specifications
(EC)Manufacturer (OEM): CWT
Max. DC Output: 850W
Efficiency: 80 PLUS Gold, Cybenetics Gold
Noise: Cybenetics A- (25 - 30 dBA)
Form Factor: ATX12V v2.53, EPS 2.92
Cooling: 140mm Magnetic Levitation Fan (NR140ML)
Modular: Fully modular
Connectors: 3x EPS, 4x PCIe
Warranty: 10 years
Reasons to buy
+Full power at 47 degrees Celsius+High overall performance+Quiet operation+Long hold-up time+Magnetic Levitation fan+Ten-year warranty
Reasons to avoid
-High OCP triggering points on the minor rails-Transient response at 3.3V could be better-Short distance between the peripheral connectors-Small distance between peripheral connectors

It wasn't easy to upgrade a platform that was among the best in the Gold efficiency category, but Corsair managed to do this with CWT's help. The new Corsair RM850x achieves higher overall performance than its predecessor thanks to its amazing ripple suppression, tighter load regulation, and higher efficiency, especially at light loads. The hold-up time is also longer, while inrush currents remain at the same low levels. The only sections where the old RM850x prevails are transient response at 3.3V, which is not of great importance, and noise output because of the more aggressive fan speed profile and the new ML fan of the new unit. Despite the increased overall noise output, we still prefer the new ML fan because it is super reliable even under high operating temperatures. 

Read: Corsair RM850x (2021) Review

Alternate Best PSU 850W: XPG Core Reactor 850W

Corsair AX1000

6. Corsair AX1000

Best PSU: Up to 1250 Watts

Specifications
Manufacturer (OEM): Seasonic
Max. DC Output: 1000W
Efficiency: 80 PLUS Titanium, ETA-A+
Noise: Cybenetics A (20 - 25 dBA)
Form Factor: ATX12V v2.4, EPS 2.92
Cooling: 135mm fluid dynamic bearing fan (HA13525M12F-Z)
Modular: Fully modular
Connectors: 2x EPS, 8x PCIe
Warranty: 10 years
Reasons to buy
+80 PLUS Titanium efficiency+Solid build quality+Excellent results through our benchmark suite+Fully modular+8x PCIe &amp+2x EPS connectors+Sleeved cables+Selectable semi-passive mode+10-year warranty
Reasons to avoid
-Expensive-EPS connectors should use 16AWG wires-Short distance between the peripheral connectors-OCP triggering points on the minor rails should be set lower

Corsair's AX1000 is one of the best 1kW power supplies available. If you want the highest possible performance matched with quiet operation, don't hesitate to make it the centerpiece of your next build (provided the price doesn't scare you off).

This beastly PSU offers tight load regulation on all of its rails, amazing ripple suppression, and crazy-high efficiency levels. Its transient response is impressive, so we're not surprised that it takes the lead from Seasonic's 1000W 80 PLUS Platinum- and Titanium-rated models (even though they're built using the same platform with slight modifications).

Read: Corsair AX1000 Review  

Alternate Best PSU 1K Watts: Thermaltake Toughpower Grand RGB 1200W

be quiet! Dark Power Pro 12 1500W

(Image credit: be quiet!)

7. be quiet! Dark Power Pro 12 1500W

Best PSU Above 1250-1500 Watts

Specifications
Manufacturer (OEM): CWT
Max. DC Output: 1500W
Efficiency: 80 PLUS Titanium, ETA-A+
Noise: Cybenetics A- (25 - 30 dBA)
Form Factor: ATX12V v2.4, EPS 2.92
Cooling: 135mm fluid dynamic bearing fan (BQ SIW3-13525-HF)
Modular: Fully modular
Connectors: 2x EPS, 10x PCIe
Warranty: 10 years
Reasons to buy
+Strong overall performance+Silent operation+Low vampire power+Lots of connectors
Reasons to avoid
-Expensive-Not as efficient as other PSUs in this price range

If you want silent operation and high-power output, the be quiet! Dark Power Pro 12 with 1500W max power fits the bill. It sports extremely high build quality and its semi-digital platform, offers top performance and can handle high operating temperatures. The only problem is the high price, but in systems that require this much power, the power supply is usually among the least-expensive parts when compared to the installed CPUs and GPUs. 

Read: be quiet! Dark Power Pro 12 1500W Power Supply Review

Corsair AX1600i

8. Corsair AX1600i

Best PSU Above 1500 Watts

Specifications
Manufacturer (OEM): Flextronics
Max. DC Output: 1600W
Efficiency: 80 PLUS Titanium, ETA-A+
Noise: Cybenetics A (20 - 25 dBA)
Form Factor: ATX12V v2.4, EPS 2.92
Cooling: 140mm Fluid Dynamic Bearing Fan (NR140P)
Modular: Fully modular
Connectors: 2x EPS, 10x PCIe
Warranty: 10 years
Reasons to buy
+Full power at 48°C+Powerful &amp+efficient+Ripple suppression+Load regulation+Hold-up time+Accurate Power Ok signal+Silent+Quality caps+Fully modular+Lots of connectors+Quality fan +Magnetic side covers
Reasons to avoid
-Expensive-Small distance between peripheral connectors-EMI with AVG detector

We waited years for a competitor to dethrone Corsair's AX1500i, and in the end it was another Corsair power supply to post higher overall performance. The Corsair AX1600i is the best PSU that money can buy today, period. It offers top performance in all areas and uses an innovative platform, which provides a glimpse at the future of power supply design.

The use of a cutting-edge PFC circuit in combination with a fully digital platform seems to be the key for record-setting performance. Besides its super efficiency, the AX1600i also offers great load regulation, amazing transient response, a long hold-up time, and unparalleled ripple suppression. Moreover, the great benchmark results are accompanied by quiet operation, enabled by a relaxed fan profile and a high-quality FDB fan. Using the Corsair Link software, you're able to choose between three fan modes: performance, balanced, and quiet.

Read: Corsair AX1600i Review

Alternate Best PSU Above 1500 Watts:  SilverStone DA1650 Review

Corsair SF750

9. Corsair SF750

Best SFX PSU

Specifications
Manufacturer (OEM): Great Wall
Max. DC Output: 750W
Efficiency: 80 PLUS Platinum, Cybenetics Platinum
Noise: Cybenetics A- (25 - 30 dBA)
Form Factor: SFX, EPS 2.92
Cooling: 92mm Rifle Bearing Fan (NR092L)
Modular: Fully modular
Warranty: 7 years
Reasons to buy
+Powerful+Efficient+Great ripple suppression+Tight load regulation+Quiet operation+Fully modular+7-year warranty
Reasons to avoid
-Expensive-Low hold-up time-Semi-passive mode can’t be deactivated

The Corsair SF750 is the strongest and one of the best SFX power supplies that money can get you today. If you want so much power out of such a small PSU and you can afford its stiff price, there is no other option. It can easily support a potent gaming system and thanks to the couple of EPS connectors that it has, and is compatible with high-end mainboards that need more juice in the CPU's area.

If you don't need more than one graphics card connector, you should consider the top-notch SF600 Platinum instead and save yourself some serious money. Corsair has set the so high in the SFX market that even SFX pioneer SilverStone, doesn't have, for the moment at least, a competing 750W SFX model in its portfolio.

Read: Corsair SF750 Review

Alternate Best SFX Power Supply: Corsair SF600 Platinum

Silverstone SX1000 Platinum (Image credit: Tom's Hardware)

10. SilverStone SX1000 SFX-L

Best SFX-L PSU

Specifications
Manufacturer (OEM): Enhance Electronics
Max. DC Output: 1000W
Efficiency: 80 PLUS Platinum, Cybenetics Platinum
Noise: Cybenetics Standard+ (35 - 40 dBA)
Form Factor: SFX-L, EPS 2.92
Cooling: 120mm Double Ball Bearing Fan (B1201512HB)
Modular: Fully
Connectors: 2x EPS, 6x PCIe
Warranty: 5 years
Reasons to buy
+High build quality+Extremely high power density+Efficient platform+2x EPS and 6x PCIe connectors+Ten-year warranty
Reasons to avoid
-Expensive-High turn-on 5VSB voltage-Low efficiency at light loads-Noisy under high loads

The SX1000 is the strongest small form factor PSU on the market today, and in reality, it is way stronger than its paper specs since we pushed it up 1480W. This is 148% above its nominal capacity! Enhance, the OEM behind this platform delivered a solid unit to SilverStone, with quite good build quality and top-notch parts. 

This is also shown by the provided warranty, which at five years is pretty long, given this unit's insane power density score. In other words, the SX1000 is a small, only in dimensions, power factory, able to support everything you throw at it.

Read: SilverStone SX1000 SFX-L

Alternate Best SFX-L Power Supply: SilverStone NJ450-SXL

Finding Discounts on the Best Power Supplies

Whether you're shopping for one of the best power supplies or just looking for an affordable alternative, you may find savings by checking out our lists of the latest Corsair coupon codes, Newegg promo codes and Micro Center coupons.

Aris Mpitziopoulos
Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.
  • abryant
    Archived comments are found here: http://www.tomshardware.com/forum/id-3694061/psus.html
    Reply
  • DVJ Rick Kraft
    Now many motherboards require 8pin+4pin CPU power, and some even require 8pin+8pin. Since this guide is made for DIY builders, this is the most important information when buying PSUs. In your guide there should be some differentiation between limited power supplies (1x CPU 8Pin) and PSUs that are more versatile, especially since 2x CPU 8pin is required for mid-tier or higher-end motherboards.
    Reply
  • davidm.maya
    21490758 said:
    Now many motherboards require 8pin+4pin CPU power, and some even require 8pin+8pin. Since this guide is made for DIY builders, this is the most important information when buying PSUs. In your guide there should be some differentiation between limited power supplies (1x CPU 8Pin) and PSUs that are more versatile, especially since 2x CPU 8pin is required for mid-tier or higher-end motherboards.


    Yes, That's true. But I had read that the 4pin connector isn't needed if you don't do 'extreme' overclocking, I don't know how much is considered 'extreme' but at least it should be safe to connect only the 8pin for runing the CPU at stock speed.
    Reply
  • jdcranke07
    If you are running a non-k SKU of Intel processors, you probably can run with DavidM.Maya's advice. I would error on the side of caution otherwise. I also agree that the number of CPU cables with pin counts & number of SATA & Molex power cables should be in there as well. The reason you might go for a high wattage PSU like a 1600W might be for a rig that has multiple purposes, i.e. gaming rig & workstation and/or server. Peripherals such as HDDs & SSDs can determine which PSU better fits you based on cables provided.
    I have an EVGA SuperNova 1600 T2 that came with 4way SATA power cables (x2) & one cable that was 2 SATA power & 2 Molex power as an example.
    Reply