A Power Supply Unit (PSU) may not be as exciting or glamorous as a brand new graphics card, but that doesn’t mean you can skimp out on it. Your power supply is the beating heart of your PC’s components, and if you buy a cheap one, it threatens to take out your entire computer!
Let’s explore what you need to know about PSUs when building your own PC.
1. Continuous Wattage Is Better Than Peak Wattage
Wattage is the base number to help you distinguish which PSU you need and how it is rated. Simply put, this is the total amount of watts the PSU can deliver to the different parts of your PC. You’ll find models that provide 300W and some that go all the way up to 1200W.
While models will advertise this number proudly on the box, it might not tell you the full story. Let’s say you see a 500W power supply. If it states Continuous Wattage, that’s great. If it’s the Peak Wattage, you might want to avoid it. You can usually check which it is on the model’s specifications page.
Continuous Wattage and Peak Wattage are ratings based on tests by the manufacturer. Continuous Wattage indicates that it can deliver those 500W continuously without fluctuations. Peak Wattage indicates 500W is the maximum power it can deliver, but probably only for a minute before dropping down.
In simple buyer terms, look for continuous wattage ratings, ignore peak wattage ratings, and ignore a product that doesn’t advertise its continuous wattage rating. If you can’t tell which one it is, don’t take your chances. Just move on.
2. How Many Watts Do You Need?
Not all PCs are built alike, so the amount of power each one needs is different. A high-end gaming PC will need more watts to run than a simple home office PC. This is because powerful processors and graphics cards require more power to run.
If you purchase an underpowered PSU, your PC will lose power during intense processes. But how do you calculate the amount you actually need? Fortunately, the internet is full of resources you can use to calculate your computer’s power needs.
Try Outervision’s Extreme Power Supply Calculator or Cooler Master’s Power Supply Calculator. If you know what you’re doing, Cooler Master’s version is better, but if you’re unsure what parts the calculator is asking for, stick to Outervision’s basic calculator.
Both calculators will give you an idea of how much wattage you need, and depending on how you entered your information, feel free to round it up to the closest PSU.
In fact, you could even go two rungs higher. For example, if the calculator says you need 370W, then a 400W PSU should be fine but 500W wouldn’t be bad either. This goes double if you plan on adding more parts in the future.
3. Save Energy With True Rated PSUs
With our society’s need for constant energy, buying eco-friendly electronics helps the planet. Even if you don’t care about nature, or you use a 100 percent green energy supplier, a true rated PSU will still save you big bucks on your energy bill.
So, what is a true rated PSU? When it’s working away, a PSU is taking AC power from the outlet and converting it to DC power, which is then sent to all the parts.
Typically the PSU wastes some energy in the conversion process. Therefore, PSU efficiency is about how much it can convert and how little it wastes.
Therefore, an 80 percent efficiency indicates it can convert 80 percent of the AC power to DC. Similarly, 50 percent efficiency indicates it converts 50 percent of the AC power to DC. In even simpler terms: a higher efficiency percentage is better and will require less power from the outlet.
The most efficient PSUs are the ones that come with an 80 Plus rating, which is assigned by an independent certifier. Even in 80 Plus PSUs, there are different levels: 80 Plus, 80 Plus Bronze, 80 Plus Silver, 80 Plus Gold, 80 Plus Platinum, 80 Plus Titanium. (These are ordered from worst to best.)
An additional advantage of these efficient PSUs is that they generate far less heat than other PSUs and usually run at quieter volumes, too. Manufacturers will advertise 80 Plus certified PSUs proudly, but if you’re having trouble finding information, check the full list of 80 Plus PSUs.
4. Figuring Out the Minor Details
Everything up to now has just been about the bare basics of PSUs. As with any technology, you can geek out and get a lot more specific about what you want or need, but if you are a beginner, the aforementioned three aspects will matter the most to you in your buying decision.
That being said, there’s some other jargon you might encounter while shopping for a PSU. Some of them don’t matter much to people new to PSUs, and some of them are very important; as such, it’s a good idea to learn what to ignore and what to pay attention to.
- AT vs. ATX vs. mATX: Sometimes, you’ll see power supplies designed for “AT,” “ATX,” or ”mATX” computers. These terms are used to describe motherboards of different sizes and designs and thus have different power needs. Double-check which motherboard you have (it should be listed in the specifications under “form factor”) and buy a PSU that matches it.
- Rails: You can get multi-rail or single-rail PSUs. Both have their pros and cons, and you don’t need to worry about the technicalities right now. If you live in an area where power fluctuations or outages are normal, you should consider multi-rail. For any other scenario, or if you use a good uninterruptible power supply (UPS), get a single-rail PSU.
- Voltage Stability: If you’re ticking all of the above boxes, then voltage stability won’t be an issue. This basically refers to the PSU’s ability to keep supplying power at 12V without dropping.
- Cabling or Connectors: Unless you’re buying a high-end specialized PSU, you should be fine with the cabling that comes in the box. High-end PSUs offer something called “modular cabling,” which lets you fit custom cables and pin connectors to attach your parts to it. Not important for the average user.
- Repair Units and Accessories: You don’t need a wattage tester or guides on how to fix a PSU. If you diagnose a problem with the PSU, your only option is to replace it and hope that it’s still under warranty.
5. Why You Shouldn’t Cheap Out
So why are we harping on about buying a quality PSU instead of just going with whatever came bundled with your PC case or a relatively unknown brand’s models?
As we said above, your PSU affects every part of your computer system and can end up frying circuits in the case of a power fluctuation.
But apart from that, quality PSUs have other benefits that make them worthwhile. Here are a few:
- They last a long time. No, really. The chances are that if you buy a quality PSU right now, rated about 100W to 200W higher than what you currently need, then you’ll be able to use it for your next PC upgrade as well. At the very least, it’ll last you several years.
- They have resale value! Upgrading to a new PSU? You’ll find buyers for your old one on Craigslist and eBay. Heck, you could even repurpose it as a bench power supply for DIY projects.
- Standardized sizes let you get creative with old PSUs too. Since all PSUs are generally shaped the same, just find a simple case, and you can make yourself a cool and quiet media center.
6. Where to Find Reliable Reviews
Manufacturers release new PSU models all the time, and it’s a relatively niche computer part for tech reviewers. Here are a few well-known and reputable brands to start you off: Corsair, Cooler Master, Antec, Be Quiet, Seasonic, and XFX.
Once you’ve gone through the aforementioned steps, you should have a fair idea of how many watts you need, which trusted brand models are certified 80 Plus for that wattage, and what fits in your budget. Now it’s time to actually do some research.
The JonnyGuru Forums are packed with reviews and feedback on power supply units and are well worth searching for your PSU make and model. You can also head over to /r/buildapc on Reddit to find out which PSUs people are leaning towards, not forgetting our own roundup of the best PSUs for PC builders.
Choosing Your First PSU
The world of PSUs can be very confusing, but you can always choose the best for your PC once you know the basics. Now you know the basics and what to look out for.
After you bought your PSU, be sure to take good care of it, as it’s one of the PC parts that tend to die. Fortunately, there are ways to extend its lifespan to get the most out of your purchase.
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