Now that you've picked out your CPU, it's time to start picking out the rest of your system components. And perhaps the most humble but overlooked of these components is the power supply unit (PSU). Available in a wide range of sizes and power capacities, there are a number of great PSUs out there, but choosing between them can be a challenge. So today we're bringing you our annual PC power supply guide, to help you sort figure out what the best options are, be it a low-wattage unit for a small form factor PC, or a hulking kilowatt unit for the most powerful PC.

AnandTech PC Power Supply Recommendations: 2017
(Prices are Nov-17 or MSRP)
Output Range Performance Option Value Option
Under 400 Watts Seasonic SS-400FL2 $100 Seasonic SSP-300ST $35
400-600 Watts Seasonic SS-520FL2 $120 Corsair CX550 $30*
600-800 Watts Corsair HX750 $116 Riotoro Onyx 750W $80
800-1000 Watts Seasonic PRIME Titanium 1000W $260 BitFenix Whisper M 850W $94
Over 1000 Watts Corsair AX1500i $414 Cougar GX1050V3 $138
*after rebate

We've split our recommendations into five main wattage categories with at least two units for each. One selection will be based on the maximum possible value (e.g. bang for the buck) and one will focus on the best overall performance. The following paragraphs expand on the proper selection of a PSU and details on why these units are our recommendations.

How Much Power Do I Really Need?

When shopping for a PSU, it is very important to be aware of your system’s power consumption and to consider of any forthcoming planned upgrades. All current computer PSUs are designed to deliver optimal performance at (or almost at) half load. It is a common misconception that a more powerful PSU will be a better choice, as the power quality and efficiency of all modern PSUs dwindles at very low loads. This is especially true at the low-end of the loading curve – usually below 15% of the unit's rated capacity – where efficiency outright plummets.

As a result, using too powerful of a PSU will result poor power efficiency, which could very well be significantly worse than what a product at a fraction of the price would deliver. It is wise to remember that the advertised performance of a PSU is within the nominal load range (20% to 100% of its rated capacity) and the manufacturer is not obliged to include information on how much the performance degrades at sub-20% load conditions. Only the 80Plus Titanium guidelines dictate an efficiency requirement of 90% at 10% load. Therefore, the selection of a severely oversized PSU is both economically and practically senseless.

Overall, the best way to select a PSU is based on both objective (e.g. wattage, performance) and subjective (e.g. design, modular cables) parameters. This admittedly does require every builder to be capable of making at least an educated guess about the power requirements of the system. However this is where our guide and advice come in.

Perhaps the biggest mistake that many users make in selecting PSUs is overrating the power requirements of their systems. It is not uncommon for people – even store salespersons and experienced builders – to recommend a 1kW unit to a user with just two (or even one) high performance GPUs. A system with a single CPU and a single GPU rarely requires more than 300 Watts. A modern Intel Coffee Lake-based system with a single AMD RX 570/NVIDIA GTX 1060 card will hardly reach up to 220-230 Watts, while it usually idles at 45-55 Watts.

Meanwhile "wattage calculators", though an improvement from blindly guessing, are usually simple tools that get their numbers from the design power (TDP) specifications of components. The TDP of a component does not represent the actual power requirements of a component -  it's at best a broad guideline - and it also is next to impossible to place every single component of a system under maximum stress simultaneously. However, keep in mind that a PSU needs to operate at half load for optimal performance. With that in mind, while the recommendations of the online tools and calculators may be overestimated, they're not overly so. Selecting a unit of the wattage they recommend is not usually a bad idea, as the recommendation usually is twice the actual power requirements of the system. The common mistake is that users usually seek to buy a significantly more powerful unit, thinking that having extra power helps, and end up with a severely oversized PSU for their system that will be both more expensive to purchase and unable to perform as it should.

If you can measure the actual power requirements of your system, keep in mind that you should not buy a unit that will frequently operate near its maximum capacity. Just as you would not run your car constantly near the red line, a PSU should not be under maximum stress for prolonged periods. A high quality PSU can withstand it, but just because it can does not mean it should. Again, all switching PSUs deliver their maximum efficiency at roughly 50% of their rated capacity. Running a PSU at over 90% capacity for prolonged periods of time will not only reduce its performance but it will also make it hotter, louder, and decrease its expected lifespan.

< 400 Watts
Seasonic SS-400FL2($100)
Seasonic SSP-300ST($35)

Although it is unlikely that most enthusiasts will even look at products rated at or under 400 Watts, the truth is that these are the ideal products for modern low-energy PC with a mainstream CPU and an average gaming GPU (or no GPU). Sadly, it is not a very popular segment of the market and there is little competition, meaning that there is not a very wide selection of products for the users.

For a low-cost product of reasonable quality that is backed up with a warranty from a reputable manufacturer, our recommendation would be the Seasonic SSP-300ST. Although it looks far too simplistic, with an unpainted chassis and bare color-coded wires, the SSP-300ST is one of the very few <400W units that is based on a relatively modern platform and not a design that is over a decade old. It has an 80Plus Bronze efficiency certification and Seasonic covers it with a 3-year warranty. $37 will not get you anything better than that.

If you found the Seasonic SSP-300ST is a little too simple, a reasonable recommendation would be the PC Power & Cooling Silencer 400W. It is an aged design and performs about as well as the SSP-300ST, but $76 will get you an attractive semi-modular PSU. With only a handful of companies offering high performance PSUs in this segment of the market, modern designs are but a handful and very expensive. Seasonic currently offers the best 400W PSU available, the passively cooled SS-400FL2 Platinum, but its $100 price tag will drive all but the most demanding users away.

400 to 600 Watts
Seasonic SS-520FL2($120)
Corsair CX550($30)

Unlike the ostracized <400 Watt range, there is a great demand for 400 to 600 Watt PSUs and, therefore, a vast selection of products available. This is the sensible power range for a typical home entertainment/gaming PC with a single GPU card.

There are many interesting options in this power range but our best value recommendation this year goes to the Corsair CX550. It is based on a relatively old platform and only has an 80Plus Bronze efficiency certification, but is currently on sale for just $30 after rebate. For users who want a reliable PSU that will get the job done, we could not find a better deal than this.

Most top performance units in this power range are at or above the $100 mark. The one that stands out is the fanless Seasonic SS-520FL2 that currently retails for $120. It definitely is an expensive unit but is 80Plus Platinum certified, fully modular, entirely fanless, and covered by a 7-year warranty. If you are going to spend $100 for a high performance PSU, you might as well go the extra mile and spend $120 for a top-quality fanless unit.

600 to 800 Watts
Corsair HX750($116)
Riotoro Onyx 750W($80)

PSUs with an output between 600 and 800 Watts are very popular amongst gamers and overclockers. They are powerful enough for dual GPU gaming systems and provide enough overhead for serious overclocking and mods. This power band is also popular among users that will be using just one GPU, as the power overhead frequently creates a feeling of security.

Our recommendation for those seeking to combine performance with value is the new Riotoro Onyx 750W PSU, as it offers a great balance between aesthetics, performance, and quality. It is based on a recent Great Wall platform and is unexpectedly efficient despite its mediocre rating. It currently retails for $80 including shipping, which is a reasonable price for a quality 750W PSU.

There are many contenders in this power range that we could recommend based solely on their electrical performance. If we are to take into account the value of the product however, our recommendation surely is the Corsair HX750. The latest revision has exceptional electrical performance and is of outstanding quality, yet its retail price is a very reasonable $116 including shipping. The HX750i with the Corsair Link interface will cost $40 higher and we do not recommend it unless some specific application makes the constant software monitoring of the PSU a necessity.

800 to 1000 Watts
Seasonic SSR-1000TD($260)
BitFenix Whisper M 850W($94)

This power range should be reserved for users that want to power high-end dual GPU computers. We cannot go very cheap in this power range because we believe that long-term reliability is an absolute must whether we are considering a high-end gaming system or a professional workstation.

The new BitFenix Whisper M 850 Watt PSU is a relatively inexpensive but highly effective choice in this power range. It is a bit aesthetically blunt but $94 will get you a fully modular 80Plus Gold certified PSU that is based on a modern Channel-Well Technologies platform. There are no other units retailing for less than $100 that we could easily recommend.

For those that seek top electrical performance regardless of the cost, Seasonic has you covered. The new PRIME Titanium units have mythical performance but also equally unreal price tags. The SSR-1000TD PRIME Titanium 1000W unit currently retails for $260 but its electrical performance is undoubtedly unmatched by any other product currently in the market.

Over 1000 Watts
Corsair AX1500i($414)
Cougar GX1050V3($138)

If you require a PSU with this kind of output, chances are that you have at least two extensively overclocked high-end GPUs and/or a seriously powerful dual-CPU system with a lot of devices. These PSUs also find use in advanced servers and cryptocurrency mining systems. That being said, the PSU is going to be powering a rather expensive system, the function of which is frequently very important.

Considering the above, the selection of a "value" PSU within this power band is a complex procedure, as the PSU has to meet high reliability standards. It is very difficult to find any quality units that cost less the $200 in this power range. Possibly the sole exception is the new Cougar GX1050V3, a modern 80Plus Gold certified unit that retails for $138 + shipping. There is currently no other unit matching its performance and/or its quality anywhere near this price range.

For users that want the absolute best and cost is not an issue, the Corsair AX1500i has been the undisputed performance champion over the past several years. Seasonic and their new PRIME Titanium series are serious competition against Corsair’s flagships, but Seasonic does not have any relevant units with a power output as high as the AX1500i does. There is virtually no other >1200 Watt PSU available today that combines the quality, performance, efficiency, and features of the AX1500i. The only problem is that the AX1500i currently retails for $400, which is enough to buy a complete mainstream system.

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  • FaaR - Friday, November 17, 2017 - link

    Dunno BEST best quiet PSU, but a really good one is Corsair RMi series. Super stable voltage regulation, super low ripple, high efficiency (gold standard, bordering on platinum), and plenty premium features like voltages, current, temps, fan monitoring via software, lots of protection features, voltage feedback sensing wires for all voltages on the ATX plug as well as filtering caps on all the major power plugs. And semipassive design with low noise fancurve and durable 4-pin fluid dynamic bearing fan. Really good PSU. Looks nice designwise too... : P Reply
  • Outlander_04 - Tuesday, November 21, 2017 - link

    The 300 watt seasonic in my htpc is silent despite having a fan Reply
  • wumpus - Friday, November 17, 2017 - link

    "Performance" in power supplies looks painfully silly. It really looks like a typical computer guide where a user simply expects to throw x amount of money into each checkbox without any determination about what they are buying.

    A power supplies produces the right mount of current to maintain the voltage at a set voltage. Any two power supplies that both keep the voltage in the specs for the motherboard and video card, will produce *exactly* the same response from the computer (unless the motherboard or video card are so poorly designed to operate out of spec). The only other issue is the efficiency of the supply, and if the "value" supply has a bronze rating, don't be certain that the "performance" job has any better efficiency.

    PS: I'd expect the power tool at pcpartpicker.com to be pretty good. Note that if twice the expected "nominal" draw is higher than that (seems unlikely), you probably should go with that number. Heavy gaming (and video boards that limit "abusive computing") could easily push above your "half the absolute maximum", assuming the GPU consumes most of the rated power.
    Reply
  • Arbie - Friday, November 17, 2017 - link

    ""Performance" in power supplies looks painfully silly. It really looks like a typical computer guide where a user simply expects to throw x amount of money into each checkbox without any determination about what they are buying."

    Well, it *is* a buyers guide, right? And it does discuss efficiency and how to choose a power level. What more would you expect? The term "performance" is clearly used just to differentiate between the cheapest reasonable choices and those with more extras and (possibly) some better components. Jeez.
    Reply
  • airdrifting - Friday, November 17, 2017 - link

    Efficiency differences at 400 watt between 80 PLUS and 80 PLUS gold makes little difference and I can assure you people do NOT care at this range. At higher range like 1000 watt, Those good power supplies are either 80 PLUS gold or 80 PLUS platinum, Which again makes very little difference in numbers. I would take a more reliable 80 PLUS gold 1000 watt power supply over a less reliable 80 PLUS platinum 1000 watt power supply any day. Higher efficiency is good, But it does not mean a better power supply (Better as in more reliable). Reply
  • E.Fyll - Tuesday, November 21, 2017 - link

    "A power supplies produces the right mount of current to maintain the voltage at a set voltage. Any two power supplies that both keep the voltage in the specs for the motherboard and video card, will produce *exactly* the same response from the computer (unless the motherboard or video card are so poorly designed to operate out of spec)."

    I'm afraid that it is not nearly as simple as that.

    The term "performance" includes the power quality and thermal performance of a PSU.

    The power quality refers to the ability of the PSU to deliver a stable, noiseless output. Voltage ripple and noise have an impact on the longevity of the powered components.

    Thermal performance includes the noise output and internal temperatures of a PSU. These two need to be, at the very least, balanced. On one hand, you do want a quiet PSU but, on the other hand, you need one capable of maintaining low internal temperatures as well. A quiet PSU is not necessary a good PSU if the internal temperatures are too high. High internal temperatures have a serious degrading effect on the unit's longevity and aging. Very high internal temperatures can result to a maximum power loss of ~>0% per year, meaning that your "just as good" 500W PSU can end up being a 365W PSU in just three years time. Also, for every 10°C, the longevity of most passive electronic components is approximately halved. This means that if a PSU were to function for 10 years at 50°C, it will function for 5 years at 60°C.

    So, two power supply units that do provide enough current and "keep the voltage in specs" are not necessarily equal. Actually, they almost never are.
    Reply
  • airdrifting - Friday, November 17, 2017 - link

    The moment I saw a 400 watt power supply with $100 price tag is recommended, And power supplies are divided into "Performance" and "value" category, I stopped reading. What kind of amateur wrote this piece of work? Those recommendations are so idiotic that I actually registered an account just to post here.
    A good power supply is a reliable one that will last you many years and won't fry anything when it goes out, Like the Corsair HX520 (made by Seasonic) I had for 8 years died in 2014. Maybe you can divide them by modular or non-modular, But the last thing people look for is "performance" in 400 watt power supply range. I assume all PSUs on the list has active PFC and 80 Plus, So they either deliver the power at rated wattage with stable voltage or not. Is a 400 watt performance power supply going to output 600 watt? I think not. What I know is you can get a very decent 750 watt power supply for $100, So why recommend a 400 watt power supply at $100?
    Also Corsair has been switching their OEM every once a while (usually for the worse), They do not have a consistent quality on any of their products whether it's high end. CX550 is pure junk. Recommending AX1500 is extremely amateur and irresponsible seeing how many of those failed based on other site reviews. If you want to be safe, It's always SeaSonic. Supernova series also seems to be pretty good right now. Just look to see which power supply gets sold out during a mining frenzy, That's the one you want since it's approved by miners who run 7 video cards 24/7.
    Reply
  • Ryan Smith - Friday, November 17, 2017 - link

    "I know is you can get a very decent 750 watt power supply for $100, So why recommend a 400 watt power supply at $100?"

    Hi airdrifting,

    If you haven't already, I highly encourage you to read the section on "How Much Power Do I Really Need?". A midrange system only draws a couple-hundred watts, so a large power supply is going to be rather inefficient for such a system.
    Reply
  • airdrifting - Friday, November 17, 2017 - link

    You clearly missed my point or you purposed tried to misinterpret what I am saying. For $23 after rebate, I can get a Seasonic S12II 520W that's more than enough for most midrange system. Even without rebate it's less than $50. You do NOT need to spend $120 to get a "performance 500 watt power supply", Reply
  • JonnyDough - Tuesday, December 26, 2017 - link

    Hi. IT pro here. My first PC was a single core 866mhz PIII from Dell. I never bought another OEM PC since then, but I have built about 40 of my own. I own a dozen gaming PCs currently, because I can and enjoy building and modding.

    I agree with you. Corsair makes many good and affordable PSUs that last for years and don't take out the components if/when they go. I've owned Enermax quality lines that kill video cards, and own a couple Thermaltakes and Seasonics, and even a RAIDmax that works just fine on an older Core2Quad system I don't care much about. The majority of my PSUs I spent $70 or less on. Many were in the $35 range after a rebate and work great. $100 for a PSU that outputs merely 400w is way overkill on price. I understand that people making $32K a year (*average US income) can probably afford that, but that doesn't mean they should. It also doesn't mean they're supporting a family, or that the majority of people aren't a lot more budget conscious than that.

    In general, I assume the PSU will support the CPU I want if it's a relatively new model, a quality name brand (which not everyone knows), and has the connectors I need. However, the GPU is worth a look. Not only does it need to be have the proper connectors do a dual card or beefy single card setup, but it also needs to be able to supply the amperage if it's a dual beefy card setup (ie has one 6 pin and one 8 pin connector or two 8's).
    Reply

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