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How to Choose a Power Supply for a Gaming PC

What Features to Look for in a Good PSU (Beginner-Friendly Buying Guide)


What to look for in a power supply for gamingThere's a few key PSU specs to understand as a beginner

Last Updated: Sep 20, 2019

Choosing the right power supply for a new gaming computer build can be confusing. Look around for advice on which PSU to buy and you'll get all sorts of responses. There'll be some who recommend buying any cheap PSU to save money, others who fiercely condone anything but buying an absolute A-list top-notch model to avoid your new system exploding within the week, and everything else in-between. So, what's the real answer?

Is choosing a good PSU really that important when building a gaming PC? Can you get away with a lower-cost budget unit? And what do all the features and specs mean anyway? Is an 80 Plus Bronze rated PSU good enough? How much extra wattage should you account for? All fair questions, and without a doubt picking a PSU rates up there as one of the more confusing hardware component selections when planning your first gaming PC build.

You don't need to understand all PSU specs in detail to be able to choose a power supply, but if you have any burning questions chances are we'll cover them in this guide so let's get into it and take your power back. After reading you'll literally know more about PSUs than 95% of gamers and will never have to succumb to poor advice on a random forum ever again.

Related: How to Install a PSU (& Which Way to Face)






Does the Power Supply Matter for a Gaming PC?

Choosing the right power supply for a new gaming computer is an often-overlooked aspect of building a PC, especially if you're a beginner. Kinda makes sense though, right? You'd be forgiven to think that a power supply is just, well, a power supply, and that it doesn't really matter in the grand scheme of things.

“It’s just a freakin' power supply... I’ll pick the cheapest I can find to save some cash” - Joe Noob

Bad move, hombre. Some things are only as strong as its weakest link, and computers are one of those things. Whilst a power supply isn't going to directly affect gaming performance, and in some cases (pun intended) there's no need to throw down serious cash on a top of the range PSU, choosing a power supply that's of good-enough quality and reliability is important to power all your precious new PC components for years to come without putting your system (and wallet) at risk.

Pick the wrong PSU for your gaming PC and s*** might just hit the fan

Buying any random cheap PSU to save money can spell trouble real fast, and they can bring about all sorts of problems all the way from increasing your electricity bill due to low efficiency to potentially blowing up your new pride and joy (rare but it happens). With a low-quality PSU in your gaming PC, you're risking a premature failure of your unit that may take your other parts with it if you get unlucky.

There's also further downsides to a bad PSU besides higher risk to your system and lower efficiency. For example, some cheap PSUs have bare cabling which can even leak RF energy. Some are also loud as hell and will hinder the enjoyment of your new system. Then there's those budget PSUs which will overheat very easily. Moral of the story? Every time you buy a bad PSU for a good gaming PC, an innocent kitten dies somewhere in the world. Be a good person and pick a PSU that's at least of decent quality - ideally a good quality unit that's also approved by the DIY community (do your research).



How to Choose Your Power Supply Wattage

Gaming computers vary greatly, from $300 scrappy entry-level gaming builds that you probably wouldn't ever tell anyone about, to $3000+ ultimate monster PCs that you wanna brag about to your buddies on Instagram. Therefore logically, PSU power requirements vary greatly too.

As a general rule of thumb though, for most gaming PC builds these days, you'll probably need to choose a power supply that has a wattage somewhere between 450 watts to 850 watts. 95% of PC builds are going to fall within this range, unless you're either building an anomaly of a system that's either under $300 (good luck with that) which may not even need 450 watts, or an ultra extreme rig in the many thousands of dollars with a ton of extra add-ons that may actually genuinely require more than 850w (such as a multi-GPU SLI gaming PC).

However, what you wanna do is calculate roughly how much power your full list of parts will require (don't forget accessories like hard drives and any extra case fans), and choose a PSU that has slightly more wattage than what you need. So, if your parts list requires around 400 watts, then get a 500-550 watt unit to be safe, or a 600 watt one if you're confident you'll be doing a fair bit of upgrades later on. How much headroom you leave in terms of wattage doesn't just depend on the potential upgrades you plan to make, but also if you're overclocking your gaming computer which will require additional power.

Tools to Check PSU Wattage Requirements

There are online PSU wattage calculators you should use to make things easy, such as PCPartPicker's built-in wattage estimation or the Outervision Power Supply CalculatorThese tools will save you having to manually figure out how much wattage all your PC parts will need; a laborious task I wouldn't assign to a sworn enemy. But also keep in mind a common rookie mistake when choosing a PSU is actually getting one that has much more wattage than you actually need. For example, someone may be building a PC that requires roughly 550 watts, yet they go for an 850 watt unit. That's okay if you intend on many upgrades, but is likely overkill for most and you could be wasting money on something you won't ever need. Leaving a good 100-150 watts of headroom (200 if you really want) is more than enough for most.

What About Maximum Power Output vs Peak Power Output?

It won't matter to most of you choosing a power supply, but it may come up in your research and make you wonder. There's a difference between the maximum power output and the peak power output of a PSU. The maximum power refers to the continuous or stable power that the PSU can produce consistently, while the peak power is the elevated maximum surge the PSU can produce for a limited amount of time (for example 10 seconds). The important one to look for is the maximum power output.





Power Supply Size Differences Explained

Another spec to know about besides the wattage is the size of a PSU, technically called the form factor. ATX is the standard form factor (technically ATX12V) and will fit in any ATX computer case, and is what 95% of PC builds will be. 

However, while the width, height, and screw placement is the same for all ATX power supplies, the depth of the unit can vary. PSUs are usually 6 inches deep, but powerful PSUs with high wattages may be deeper, so make sure to check that your PSU fits if you're opting for a high-powered unit and placing it in a mid-tower or smaller case for example.

What Are SFX PSUs?

There's also such a thing as SFX sized power supplies (technically SFX12V) which are designed for use in small form factor cases, which might be something you need if your case only lists support for SFX units. If that's the case, pun intended, it's hard to ignore Corsair's range of SFX PSUs such as the SF600: (Seasonic's Focus SGX-650 is also great)




What is a Modular and Semi-Modular PSU?

A modular power supply is simply one with the ability to detach any excess power cables that you don't use, which leads to less clutter within your PC case, which then may lead to better overall airflow/cooling, less dust build-up, and it also looks neater (which matters if you're showing off your build with a see-through side panel case). Modular PSUs cost more than normal, non-modular units, and whether or not it's worth the higher price will depend on your personal preference. Having a chunk of leftover cables that you can simply tuck away within your case somewhere may not bother you, especially if you have a case with plenty of room to tuck them away neatly.


Modular vs Non-Modular PSUs. Modular = more expensive but less clutter

If you're on a budget and trying to cut costs as much as possible, just get non-modular if you can't find a modular unit at a price you like. Otherwise, if you're building a high-end or extreme custom gaming computer where price isn't as much of a factor, if you want the best gaming PSU you can get then always go modular as it's obviously the most convenient and will make doing power supply cable management easier. Lastly, there are also such a thing as semi-modular PSUs which is, convenience-wise, in the middle of modular and non-modular power supplies and only come pre-attached with the absolute essential power connections which means less clutter than a non-modular unit but not as much flexibility as modular ones.




Power Supply 80 Plus Ratings Explained

Power supplies have various efficiency levels which is one measure of how good a particular unit is. More efficient PSUs not only draw less power, meaning lower energy bills, but they produce less heat and therefore less noise as well. The efficiency of a power supply is given a rating, with "80 Plus" being the bare minimum rating you should go for. Meaning, if a unit doesn't have "80 Plus" mentioned somewhere then chances are you should avoid it.

There are always exceptions to the rule though, but in general opt for a 80 Plus unit or better whenever you can. There are levels to 80 Plus ratings, with basic 80 Plus, then 80 Plus Bronze, Silver, Gold, and Platinum, in order from least to most efficient. For super powerful gaming computers you'll want a gold rated PSU or better for maximum efficiency.


Not the only factor in what makes a good PSU, but ideally stick to a PSU with an 80 Plus Bronze rating


PSU Rails Explained (Single vs Dual Rail PSUs)

What are PSU rails? You don't need to understand them to choose the best power supply for your computer, but you may be curious - especially if you're deciding between different high-quality PSUs and you're wondering the difference between single vs multi rail power supplies.

If you're planning a cheap gaming PC build or even a mid-range sorta setup, you won't need to know what PSU rails are, but if you're a power user and want to be as smart about your PSU choice as possible (because as mentioned the more powerful your build the more important it is to pick best PSU you can get your hands on) then let's discuss what PSU rails are, how they work in a nutshell, and what you need to know about them.

Power supplies have different “rails” and the individual rails of the PSU can be an important factor to consider when picking the best quality PSU for a high-end PC. There is one particular rail of a PSU that is most important: the 12V rail. This one provides power to your most powerful parts including the CPU and GPU.

In a typical gaming computer the graphics card will require the most power, and so you’ll want to get a PSU that has at least 24A (amps) on the 12V rail if you have a single mid to high end GPU, and at least 34A for a high-end SLI or CrossFire setup. These are just general estimates so if you want to be super prudent about your PSU choice it's best to find out exactly what your GPU setup will require.

There are also two different types of PSUs out there: single rail and multiple rail PSUs. Single rail units have a single high-powered 12V rail to power all your parts, while PSUs with multiple rails have more than one 12V rail each with different amperage's to divide power between two or more rails.

Whether a unit has single or multiple rails doesn’t affect its overall performance, but basically, if you require a lower-power PSU such as 550 watts or less, the whole single vs multiple rails issue simply does not matter and either will be fine so long as you still pick a decent-quality unit.

But for power users, a dual/multi rail power supply will offer an extra layer of protection in case there's a short circuit, and when you start heading into extreme enthusiast territory with beasty 1000w PSUs and above, multi-rail PSUs start to become a whole lot more crucial as it's risky and dangerous to output so much power on only the single rail.



Choose a PSU With the Connectors You Need

Not all PSUs have the same connections

Another thing you may need to consider when choosing a power supply are the power connectors, as different units come with different types and amounts of cables. For most gaming PC builds, if you buy a good-quality, popular PSU and your build is a pretty standard modern setup without much extra add-ons, chances are you don't have to worry about checking the PSU connections. But for more advanced and/or higher-end builds, or if you just want to be extra safe, it's something you'll want to double check.

First of all, all computer power supplies will have either a 24 or 20+4 pin main motherboard connector, and either a 4 or 8 pin 12V connector, both of which connect to the motherboard. But what you'll want to check is that your PSU has the right type and amount of power connectors for your graphics card - if your card requires dedicated power (most mid to high-end GPUs do). Some GPUs will require just 1 PCIe 6 or 8 pin cable, while others may need 2 of these. Most modern PSUs will come with 2 6+2 PCIe cables though (which can connect to either a 6 or 8 pin GPU connector), so you should be good, but if your GPU needs 2 of these PCIe connectors then be sure your PSU does indeed have 2 PCIe connectors.

For advanced users, if you’re running multiple cards in SLI or CrossFire you'll want to also confirm your PSU is either SLI or CrossFire compatible as not all are. It should specifically be listed in the PSU specs, but keep in mind some units won’t officially list support for SLI/CrossFire but are still capable of powering multi-GPU setups (in which case you'll need to dig a bit deeper to find out if your PSU is good to go for this).

If you have a ton of accessories for your PC build, check that your PSU has enough SATA or Molex 4pin connectors for your hard drives, optical drives, and other devices like case fans (which may actually require those older Molex connectors). Most modern PSUs will come with plenty, but you never know if you have a lot of components to hook up. Lastly, if you just arrived in a time machine from 10,000 years ago and you're including a floppy disk drive in your new build, check your PSU has such a connector as floppy drives require their own type of PSU cable.

See Also: How to Connect PSU Cables (& Cable Management 101)



What Are the Best Power Supply Brands?

Sticking to known, reputable, reliable brands is important when selecting any hardware component, but especially crucial when it comes to choosing a power supply. As mentioned earlier, skimping on your choice of PSU and just haphazardly picking a cheap, perhaps generic no-name brand unit to save a few bucks is not the wisest move if you care about your computer both now and over the long haul. 

As for the best PSU brands as of the time of writing this guide (2019), some of the best PSU manufacturers overall right now would have to be Seasonic, EVGA, Corsair, Antec, XFX, Silverstone and Thermaltake (in no particular order). But here's the thing: you also have to look into the specific model as well as even the best brands in the world are capable of making slightly sub-par quality units (at least compared to other available options in that price range). All these brands have lower-tier PSUs you likely want to avoid.

Yup, even though they're one of the absolute best PSU brands, there's even a couple Seasonic PSUs I'd personally steer clear of (but yeah, most Seasonic units are top quality). Overall, sticking to the mentioned brands above is recommended if you want to choose the best PSU for your system, although the more powerful your PC the more important it is to do further research and ensure the exact PSU you choose is a good one.





Current Top PSUs for the Money (2019)

That just about wraps our guide to choosing a power supply for your new rig. If you're looking for specific PSU model recommendations, see our latest recommended gaming builds section where we always do our due diligence to only ever include good-quality, reliable power supplies. Any PSU from those sample builds will serve you well, and as you go up in build tiers they get progressively higher and higher quality because for a high-end build it's even more important to buy something that will not let you down (and that is as efficiency as possible, hence why we only recommend gold-rated PSUs as a minimum for any extreme PC build). Anyway, hope this guide helped a bit in your research and good luck. You've been warned; if your new PC build explodes like the Death Star, we cannot be held responsible ;p



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