Best Power Supply Buying Guide (Jun 2020) 118

Best Power Supply Buying Guide (Jun 2020)

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Introduction

As a reviewer I have tested hundreds of power supplies, so I created this article to help you find the best power supply. The power supply is a vital component in a PC because it supplies electrical power to every other part in your computer. If your power supply was included with the case, I recommend you swap it out for an aftermarket PSU suited to your needs. A good PSU can reward you with stable overclocks, low noise, and better cooling for other components through improved airflow. You might even be able to save money in the long run as a quality power supply will operate more efficiently, resulting in a reduction of your power bill. At the same time, a bad PSU can damage expensive components, such as motherboards or graphics cards, and possibly destroy data by damaging your storage devices.



Unlike many other "best of" articles, this guide does not contain affiliate links, so you can be sure I'm not recommending whoever pays the highest commission. The primary factor for my selection of the best power supply is its overall performance score based on my in-depth reviews. The score is derived using an algorithm I started developing many years ago. Besides just performance, the recommendations in this article also consider build quality and protection features. The price tag of the power supply is important, too, but a major factor only for the "best budget" power supply category. Furthermore, a quiet power supply will always be preferred over a noisy model.

In this article, I offer my picks for the best power supplies across various categories defined by needs and not just budget. The recommendations are backed by a wealth of testing data and pricing.

Our Best Power Supply Recommendations

The table below depicts the best PSU for every possible scenario. If you want to learn more about a specific power supply model, why we recommend it, or what the alternatives are, just click on it to be redirected to the corresponding section on the second page.

Best power supply for...
Budget & Office
(up to 450 W)
Corsair CX450
Alternative: EVGA 450 BT
Midrange Gaming
(500–600 W)
Seasonic Focus Plus Platinum 550 W
Alternative: Super Flower Leadex III ARGB Gold 550 W
Performance Gaming
(600–700 W)
Seasonic Prime Ultra Titanium 650 W
Alternative: Seasonic Focus Plus Platinum 650 W
High-end Gaming
(700–850 W)
Corsair AX850
Alternative: Seasonic Connect 750 W
Enthusiast Gaming
(850–1000 W)
Corsair AX1000
Alternative: Antec Signature 1000 Titanium
Workstations
(1000 W+)
Corsair AX1600i
Alternative: EVGA SuperNOVA 1600 T2
Small Form FactorCorsair SF450 Platinum
& Silverstone NJ450-SXL
Quietest PSUSeasonic Prime Titanium Fanless 600 W

Power Supply Shopping Tips

The most frequent questions are what wattage will be required and whether it will it be enough. There are some PSU calculators, but I wouldn't rely on them too much because even two identical parts (e.g., processors) can differ significantly in terms of power consumption, mostly under overclocked conditions, including GPUs. Power spikes CPUs and GPUs can create are another issue PSU calculators don't even touch. Some of these power spikes can lead to the PSU shutting down if any of its protection features are triggered (usually overcurrent protection). Yet another issue is the transient response of a power supply to sudden loads, which can lead to instability if poor.

The most energy-demanding component in a PC is the graphics card, and the best way to find out its power consumption is to read one of our reviews, where power consumption is detailed under various scenarios and with comparisons. There is also the Cybenetics GPU database, and of course reviews from other sites. The second-most energy demanding component is the processor. While manufacturers provide TDP (Thermal Design Power) numbers, these can often be wildly inaccurate, so the best way is to look at reviews and just add up all the numbers.

The best way to evaluate your power supply requirements if you want to replace your current unit is to use a kill-a-watt device and run an intense benchmark. The peak wattage you see will prove useful in deciding on your next PSU purchase. A safe choice is a PSU with at least 20% headroom over your peak wattage, not only for future upgrades, but also because even the best power supply delivers its highest efficiency at loads in the 30%–50% range of its maximum rated capacity.

In the past, high wattage PSUs suffered from low efficiency at light loads, but that's not true anymore. Based on the newest ATX specification, all PSUs should achieve over 70% efficiency at 10 W (<500 W units) or 2% (>500 W) of their maximum-rated-capacity load. Burst-mode operation allows modern power supply designs to be highly efficient under very light and light loads regardless of the maximum power output.

Another important factor is the PSU's size. Nowadays, most power supplies have compact dimensions. However, you should check the chassis you intend to use to see if the PSU fits, also as some chassis don't even support ATX form factor PSUs, but require SFX or SFX-L PSUs, which are much smaller.

It is common knowledge that most users prefer fully modular PSUs over semi-modular ones. Non-modular PSUs are only recommended in low-end systems where cost is a top priority, and the difference is only a few dollars anyways. A fully or semi-modular power supply allows for better cable management, which improves airflow in your system and leads to lower thermal loads. Consequently, output noise can be lower as well.

The RGB trend has made its way to power supplies as well, but this feature should be at the bottom of your list unless you are a case modder wanting to show off your nice power supply. Many cases have closed PSU compartments, so make sure you get the right chassis if you want to look at your PSU's RGB light show.

Best Budget Power Supply: Corsair CX450


Power:
450 W
OEM:
CWT (RPS0053), Great Wall (RPS0063)
Efficiency:
85% / 80+ Bronze / CWT: ETA-S, GW: ETA-A-
Noise:
CWT: 27 dBA, LAMBDA-A- / GW: 36 dBA, LAMBDA-S+
Cables:
Fixed
Length:
143 mm
Connectors:
1x EPS, 2x PCIe 6+2, 5x SATA
Cooling:
120 mm / rifle bearing / semi-passive
Price:
$55.99
Warranty:
5 Years
  • Highly affordable
  • Full protection feature set
  • Decent efficiency levels
  • Good build quality
  • Rifle bearing fan
  • 5-year warranty
  • Single PCIe connector
  • Not quiet (GW OEM)
  • Short distance between peripheral connectors
The CX450 is made by both CWT and Great Wall. The GW version offers higher efficiency, especially at light loads, and its 5VSB circuit is also more efficient. Both units use rifle bearing fans, but it is driven by a more-aggressive fan profile in the GW unit. All in all, this is a very good PSU given its highly affordable price and the protection features that work, which is the most important factor in budget power supplies. Keep in mind that due to US tariffs on everything made in China, all units sold in the US are by CWT, which also has a manufacturing line in Vietnam.

Alternatives

  • EVGA 450 BT: If the CX450 feels a bit expensive, take a look at the EVGA 450 BT, which offers the same 450 W rating, but can usually be found at a lower price.
  • Corsair CX450M: For a few more dollars, you can get the modular version of the CX450, which is made by Channel Well Technology.

Best Midrange Gaming Power Supply: Seasonic Focus Plus Platinum 550 W


Power:
550 W
OEM:
Seasonic
Efficiency:
90% / 80+ Platinum / ETA-A
Noise:
15 dBA / LAMBDA-A++
Cables:
Fully modular
Length:
140 mm
Connectors:
2x EPS, 2x PCIe 6+2, 6x SATA
Cooling:
120 mm / fluid dynamic bearing / semi-passive
Price:
$114.99
Warranty:
10 Years
  • Tolerant to high operating temperatures
  • Efficient
  • High overall performance
  • Silent operation
  • High build quality
  • FDB fan
  • Fully modular
  • 2x EPS & 2x PCIe connectors
  • Compact dimensions
  • 10-year warranty
  • Transient response on the minor rails could be better
  • Slightly higher than normal inrush currents
  • Short distance between peripheral connectors
The Seasonic Focus Plus Platinum with 550 W maximum power output is a fine power supply with a high performance-per-dollar score. It is incredibly quiet, which is also shown by the Cybenetics LAMBDA rating (A++) certification, and very compact, only measuring 140 mm long. The new versions of this unit come with two EPS connectors, so you will be able to use it with even a high-end mainboard, which needs more juice for its CPU socket area.

Alternatives

  • Super Flower Leadex III ARGB Gold 550 W: For users wanting to combine high performance and increased reliability with RGB lighting, the Leadex III ARGB with 550 W maximum power output is the only way to go. While you can manually select your RGB lighting mode, you can also connect it to a compatible mainboard and synchronize the lighting with the other RGB devices in your system.
  • Corsair RM550x: The smallest member of Corsair's RMx line offers high performance and a silent operation at even high loads and increased operating speeds. If you don't need the higher efficiency the Seasonic Focus Plus Platinum with a similar capacity offers and want something more affordable, but just as good in all other regards, the Corsair RM550x is the ideal choice.

Best Performance Segment Gaming Power Supply: Seasonic Prime Ultra Titanium 650 W


Power:
650 W
OEM:
Seasonic
Efficiency:
92% / 80+ Titanium / ETA-A+
Noise:
10 dBA / LAMBDA-A++
Cables:
Fully modular
Length:
170 mm
Connectors:
2x EPS, 4x PCIe 6+2, 8x SATA
Cooling:
135 mm / fluid dynamic bearing / semi-passive
Price:
$179.99
Warranty:
12 Years
  • Tolerant to high operating temperatures
  • Efficient
  • High overall performance
  • Operates quietly enough
  • High build quality
  • FDB fan
  • Fully modular
  • 2x EPS & 4x PCIe connectors
  • 12-year warranty
  • Expensive
  • 3.3 V transient response performance
  • High inrush current with 230 V input
  • Short distance between peripheral connectors
The Seasonic Prime Ultra Titanium is a highly efficient power supply for users who need the increased reliability and high performance, but don't mind the stiff price tag. With a 12-year warranty, the longest in the PSU market, Seasonic surely makes a point on the build quality and reliability of this product.

Alternatives

  • Super Flower Leadex III 650 W: The non-RGB 650 W version of Super Flower's Leadex III line costs less than the Prime Ultra Titanium of similar capacity and offers high performance in all areas. It might not be able to match the efficiency levels of the Prime Ultra Titanium, but its price-per-dollar ratio is pretty high.
  • Seasonic Focus Plus Platinum 650 W: For those of you who don't want to pay the premium price of the Seasonic Prime Ultra Titanium 650 W, the Focus Plus Platinum with a similar capacity is the best alternative. It offers slightly lower overall performance and has a 10-year instead of a 12-year warranty, but costs notably less.

Best High-end Gaming Power Supply: Corsair AX850


Power:
850 W
OEM:
Seasonic
Efficiency:
92% / 80+ Titanium / ETA-A+
Noise:
15 dBA / LAMBDA-A+
Cables:
Fully modular
Length:
172 mm
Connectors:
2x EPS, 8x PCIe 6+2, 16x SATA
Cooling:
135 mm / fluid dynamic bearing / semi-passive
Price:
$229.99
Warranty:
10 Years
  • Tolerant to high operating temperatures
  • Efficient
  • High overall performance
  • Long hold-up time
  • High build quality
  • Silent
  • FDB fan
  • Fully modular
  • 2x EPS & 8x PCIe connectors
  • 10-year warranty
  • Expensive
  • Some cables have in-line caps
  • It would be nice to see 16AWG gauges on the EPS connectors
  • High OCP on the minor rails
  • Short distance between peripheral connectors
The Corsair AX850 is currently the best power supply money can buy in the 850 W category. It is based on the topnotch Seasonic Prime Titanium platform, so its extraordinary performance doesn't come as a surprise. If only it were more affordable.

Alternatives

  • Seasonic Connect 750 W: A unique power supply, it is the first of its kind because of the backplane that brings the modular connections closer to the system parts. This leads to shorter cables, resulting in less trouble with cable management and routing. The added benefit is the increased airflow in your chassis because shorter cables occupy less space.
  • Corsair RM850x: Corsair's RMx line is among the most popular in today's market, and for good reason. The performance-per-dollar ratios RMx models achieve are among the highest in their respective categories, and the RM850x is no an exception. The cherry on top for this unit is the quiet operation, which is usually only the case with more expensive, higher efficiency PSUs.
  • Super Flower Leadex III Gold 850 W: Another member of Super Flower's Leadex III family manages to get nominated as the best alternative option, this time in the 850 W category. Besides good performance and high efficiency, it also features a silent operation.

Best Enthusiast Gaming Power Supply: Corsair AX1000


Power:
1000 W
OEM:
Seasonic
Efficiency:
92% / 80+ Titanium / ETA-A+
Noise:
23 dBA / LAMBDA-A
Cables:
Fully modular
Length:
172 mm
Connectors:
2x EPS, 8x PCIe 6+2, 16x SATA
Cooling:
135 mm / fluid dynamic bearing / semi-passive
Price:
$284.99
Warranty:
10 Years
  • Tolerant to high operating temperatures
  • Efficient
  • High overall performance
  • Long hold-up time
  • Topnotch build quality
  • Silent
  • FDB fan
  • Fully modular
  • 2x EPS & 8x PCIe connectors
  • 10-year warranty
  • Expensive
  • Some cables have in-line caps
  • EPS connectors should use 16AWG gauges
  • High OCP on the minor rails
  • Short distance between peripheral connectors
There is no doubt that the Corsair AX1000 is one of the best 1 kW power supplies available on the market today. Its performance is excellent in all areas, including efficiency, load regulation, ripple suppression, hold-up time, and transient response. It also operates quietly, which is why it earned the Cybenetics LAMBDA-A badge. Extremely high efficiency levels from the platform keep thermal loads low, which keeps temperatures low without pushing the fan too hard.

Alternatives

  • Antec Signature 1000 Titanium: The flagship of Antec's Signature line is also based on Seasonic's Prime Titanium platform, with the added bonus of the OC Link feature, which allows you to connect two similar PSUs and operate them at the same time should your system need extraordinarily high energy levels.
  • Seasonic Prime Ultra Titanium 1000 W: But for some minor changes, this is basically the same unit as the AX1000, so it only makes sense for its performance to be as high.

Best Power Supply For Workstations: Corsair AX1600i


Power:
1600 W
OEM:
Flextronics
Efficiency:
92% / 80+ Titanium / ETA-A+
Noise:
23 dBA / LAMBDA-A+
Cables:
Fully modular
Length:
200 mm
Connectors:
2x EPS, 10x PCIe 6+2, 16x SATA
Cooling:
140 mm / fluid dynamic bearing / semi-passive
Price:
$559.99
Warranty:
10 Years
  • Tolerant to high operating temperatures
  • Powerful
  • Cutting-edge platform featuring high build quality
  • Efficient
  • Top performance in all sections
  • Long hold-up time
  • Low inrush current
  • Quiet operation for its capacity
  • FDB fan
  • Fully modular
  • 2x EPS & 10x PCIe connectors
  • Software that allows for control and monitoring
  • 10-year warranty
  • Expensive
  • Increased EMI emissions at low frequencies
  • Short distance between peripheral connectors
If you can afford the high price tag and need this much power, the Corsair AX1600i is the perfect choice. Many of you will argue that it is incredibly expensive, but it just packs so much technology internally and does sport great build quality to boot, which has me believe it is well worth its high price tag. After all, it isn't as expensive as a high-end graphics card, and given a PSU's life cycle is much longer, I don't find it to be overpriced.

Alternatives

  • EVGA SuperNOVA 1600 T2: This is a beast of a power supply. Its platform is capable of much more power output, so it won't break a sweat even when delivering power levels close to its maximum rated capacity for prolonged periods of time. It was the favorite power supply of all hardcore miners who wanted something of extremely high quality and performance, as it can handle high loads while operating around the clock continuously. It remains the best power supply in EVGA's portfolio.
  • Corsair AX1500i: The AX1500i was the best power supply before the arrival of the AX1600i. Despite its age, it remains one of the best PSUs money can get you, and although it has a high price tag, it is still more affordable than the AX1600i.

Best SFX Power Supply: Corsair SF450 Platinum


Power:
450 W
OEM:
Great Wall
Efficiency:
91% / 80+ Platinum / ETA-A
Noise:
22 dBA / LAMBDA-A
Cables:
Fully modular
Length:
103 mm
Connectors:
1x EPS, 2x PCIe 6+2, 4x SATA
Cooling:
92 mm / rifle bearing / semi-passive
Price:
$124.99
Warranty:
7 Years
  • Tolerant to high operating temperatures
  • High overall performance
  • Efficient
  • Silent
  • FDB fan
  • Fully modular
  • 1x EPS & 2x PCIe connectors
  • Individually sleeved cables
  • Comes with an SFX-to-ATX bracket
  • 7-year warranty
  • Expensive
  • There is room for improvement in its transient response
  • Turn-off overshoot at +12V
Not only with high performance, the Corsair SF450 Platinum manages to remain quiet under even stressful conditions because of its high efficiency levels. The fully modular cabling consists of individually sleeved cables, and Corsair was kind enough to also throw an SFX-to-ATX bracket into the bundle. If 450 W are enough for your system and you need an SFX power supply, there is no need to look elsewhere.

Alternatives

  • Corsair SF600 Platinum: It uses the same platform as the SF450 Platinum, but because it delivers more power, overall performance is slightly lower. All in all, a great SFX PSU that uses the same cable configuration as the SF450 Platinum. You should only go for this unit if 450 watts are not enough for your system.
  • Corsair SF750 Platinum: The strongest SFX power supply available today, and with top performance levels in all areas. Despite its extremely high power density, it achieves an impressive LAMBDA-A- Cybenetics noise rating with close to 26 dBA overall noise output. One of the very few SFX units offering 2x EPS connectors (along with 4x PCIe connectors).

Best SFX-L Power Supply: SilverStone NJ450-SXL


Power:
450 W
OEM:
Enhance Electronics
Efficiency:
92% / 80+ Titanium / ETA-A+
Noise:
<6 dBA / LAMBDA-A++
Cables:
Fully modular
Length:
132 mm
Connectors:
1x EPS, 4x PCIe 6+2, 8x SATA
Cooling:
Passive
Price:
$189.99
Warranty:
3 Years
  • Unique design
  • The only passively cooled SFX-L PSU
  • High overall performance
  • High build quality
  • Efficient
  • Highly efficient 5VSB rail
  • Good ripple suppression
  • Fully modular
  • 1x EPS & 4x PCIe connector
  • Comes with an SFX-to-ATX bracket
  • Expensive
  • Short warranty
  • Transient response at 3.3 V could be better
  • Increased EMI at low frequencies
  • Low PF readings
  • No bypass relay for the NTC thermistor
  • No SFX-to-ATX adapter included in the bundle
This is the only passively cooled SFX-L you will find on the market today. The design is unique, both externally and internally, and performance levels are pretty high. Enhance Electronics proved that it can be truly innovative with this product. If only it were more affordable and the warranty period longer—five years would be nice.

Alternatives

  • Fractal Design Ion SFX Gold 500 W: An impressive entry from Fractal Design in the SFX-L category that utilizes a Seasonic platform—high performance at a fair price, it also operates quietly and is fully modular with highly flexible cables. The 10-year warranty and included SFX-to-ATX adapter are two more benefits.
  • SilverStone SX800-LTI: A tiny power supply in terms of dimensions only, its power density per liter is 775 W! It also achieves sky-high efficiency and good overall performance.

Quietest Power Supply: Seasonic Prime Titanium Fanless 600 W


Power:
600 W
OEM:
Seasonic
Efficiency:
92% / 80+ Titanium / ETA-A+
Noise:
<6 dBA / LAMBDA-A++
Cables:
Fully modular
Length:
170 mm
Connectors:
2x EPS, 4x PCIe 6+2, 8x SATA
Cooling:
Passive
Price:
$199.99
Warranty:
12 Years
  • Tolerant to high operating temperatures
  • Silent
  • Efficient
  • High overall performance
  • Long hold-up time
  • Topnotch build quality
  • Fully modular
  • 2x EPS & 4x PCIe connectors
  • 12-year warranty
  • Expensive
  • I expected even better transient response at +12 V
  • Short distance between peripheral connectors
If you need to build a strong system and want to make it as quiet as it gets, the Seasonic Prime Titanium Fanless 600 W fits the bill. It is expensive, but this is common for all passive power supplies. Internally, every component Seasonic used is clear overkill to allow it to operate effortlessly under all conditions.

Alternative

  • SilverStone NJ450-SXL: I already listed this unit as the best SFX-L power supply, but since it is also passively cooled, it easily wins the title for the best alternative passive PSU if availability of the Seasonic Prime Titanium Fanless 600 W is an issue or you need a compact passive power supply.
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