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What to know when buying a PC PSU Power Supply

There’s more to buying a PSU than grabbing the biggest number and going home. Each number means something, and you’d be surprised at how little you actually need for a functional gaming system, especially with modern hardware.

We’re going to break down each of the main power supply specs below and what they mean to you.

Wattage
Wattage refers to the capacity of the PSU in question. This is the first spec to look at when buying a power supply of your own, but it can be tough to pick if you aren’t sure what you need.

If you aren’t sure what your system’s power draw is, use a wattage calculator or a tool like PCPartPicker to find estimated power requirements. Once you have that, you’ll typically want to bump up by 50-100W to ensure you have plenty of flex room, especially if you intend on overclocking your CPU and/or GPU. Naturally, this holds true if you plan on doing significant upgrades in the future.

General guidelines for each tier of PSU.

400W – 600W
400W – 600W power supplies are suited for most budget and mid-range PC builds. This applies especially if they are using modern CPUs and GPUs, which consume much less power than chips from 5+ years ago. If you’re buying a replacement PSU for an older system, or a system with used parts that are a few generations old, you may want to bump up even higher.

650W PSUs are generally regarded as the sweet spot in this regard, capable of powering most mid-range systems with little issue.

700W – 900W
700W – 900W power supplies are most suited for high-end and server PC builds. Particularly old GPUs or particularly powerful CPUs (like the latest i9s and Threadrippers) also tend to require this power spec.

In some cases, it’s also worth buying these PSUs for much weaker systems, especially if they’re rated for quiet operation and high power efficiency. The less a high-efficiency PSU is being pushed, the quieter and cooler it will run.

1000W – 1500W
This tier and higher is overkill for all but the most extreme of scenarios, at least in terms of sheer wattage.

When combined with modularity and high efficiency, though, PSUs rated for this wattage are ideal for keeping temperature and noise levels low. We’ll explain a little more about efficiency in the next section.

Efficiency
Most mainstream PSUs come with an 80+ Efficiency rating, which indicates… well, the efficiency of the power supply. The better the Efficiency, the less power the system will consume on idle and during regular use.

To explain a little bit better, a 500W PSU with 0% efficiency would be running at its full capacity 24/7, regardless of what the user is doing. This would mean the same level of noise, heat, and power consumption while doing casual web browsing as playing games, which would be just plain wasteful.

Or put another way, if you have a 500W PSU with an 80+ rating, it’d use significantly less than its max power while you’re performing basic tasks.

80+ rating, what do they mean?

80+
The most basic 80+ rating indicates a bare minimum of 80% power efficiency. However, this still means a lot of excess heat and power consumption compared to other tiers. The best cheap power supplies will at least have an 80+ rating.

80+ Bronze
The 80+ Bronze rating is a moderate step up, providing a minimum of 82% power efficiency. In some scenarios, this can even go as high as 88%, but usually averages around 85%. This is a marginal improvement over 80+, but will still release excess heat and noise.

80+ Gold
80+ Gold is the sweet spot that most consumers and manufacturers alike target. The minimum efficiency here is 87%, the peak is 92%, and the average is 89%. At this point, excess heat is mostly diminished as an issue, but noise levels will still be a little high.

80+ Platinum
80+ Platinum used to be the highest standard, starting at 89% efficiency and averaging 92% efficiency. This reduces excess heat to the point where it’s barely noticeable, and noise levels get fairly quiet here, too. This is ideal for quiet PC builds and SFF builds.

80+ Titanium
The latest and greatest 80+ rating is 80+ Titanium, which starts at 90% efficiency, peaks at 96% efficiency, and averages around 94% efficiency. This is really about as good as you’re ever going to get, but who knows: maybe in a few years, we’ll have 80+ Diamond, with 100% efficiency.

Modularity
Modularity refers mainly to PSU cabling. Specifically, what cables can and can’t be removed.

Non-Modular
Non-Modular power supplies have no removable cables, which means that you’ll have a ton of excess cables in your case. This is particularly unfortunate in Micro ATX, Mini ITX, and SFF PC builds, where there is little room for cable management. This also makes for a much more difficult initial building process. You might need extra zip ties if you go this route.

Semi-Modular
Semi-Modular power supplies are the sweet spot for most people. Most cables are removable, except for the main motherboard power cable, which you probably didn’t need to remove anyway. However, it not being removable means it’s also not replaceable, which can be bad if the cable is damaged or you need a shorter cable for an ITX/SFF PC build.

This provides a much better building experience than Non-Modular and is a recommended step up if you can afford the extra ~$20 or so.

Fully-Modular
Fully-Modular power supplies are the best, no question. Every cable can be removed and replaced, which means that only the necessary cables will be inside your build at a given time. Moreover, if you need shorter ones for an ITX/SFF build, you can replace them without worry. This also provides the easiest building experience.

ATX Or SFX?
Fortunately, this is pretty simple. These refer to form factors.

ATX is the standard PSU form factor, and all except one of the PSUs listed above are in the ATX form factor. Get one of these unless you have an SFF PC build.

SFX is the SFF PSU form factor, making it ideal for Mini ITX builds and smaller Micro ATX cases.

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