Last Updated on September 29, 2019 by Dave Farquhar
If you’ve built a few PCs, or repaired a few PCs, you have some idea how important the power supply is. If you buy any old tin box that fits, you can probably expect to run into some problems. Here’s some advice on buying power supplies, including reliable power supply brands.
My story
I’ve been building PCs more than 20 years. For a time in the 90s, I even built PCs in an enterprise environment when funds were scarce. I’ve built my share of high-end PCs, and I’ve also built a lot of cheap and cheerful PCs. To some extent you can skimp on components, but there are certainly limits.
Today I live and work 300 miles from my nearest coworker, so today I manage my own corporate PC but only my own corporate PC. I also manage this web server, and home PCs for myself, my wife, and our two sons. A good power supply can last many years, so here’s how to know a good one when you find it.
Power supply basics
First things first: If you’re having trouble with your existing power supply, you can test it with a paper clip. Really. But there’s one other thing I really want you to keep in mind. Even though I have a picture of an open power supply below, don’t open a power supply. Unless it’s had a chance to discharge, a power supply can deliver you a nasty shock.
Wattage first
Before we even talk about brand, you need to use a power supply calculator to figure out what you need. There’s no reason to put a 1000-watt power supply in a PC that spends its life on social media sites. At the other extreme, if you put a $15 cheapie in a dual-video-card gaming rig, you and that power supply will have a very miserable short life together. Your computer will spend as much time rebooting spontaneously as it does anything else.
Some people will tell you that you can’t get a good power supply for less than $80. I disagree. I see plenty of perfectly good power supplies for well under $80 at my local computer store that would be overkill in the web server that serves up this blog. The key is to get the right wattage first, then find a suitable brand and model. You may actually be surprised at how much power your PC really uses. Or how little power it uses.
When price matters more than brand: under 500 watts
At the low end of the market, I don’t distinguish between brands all that much. None of the ordinary reliable power supply brands play in this space, at least not consistently.
I always walk right past the $15 power supplies. At the $20 price point, you can get something resembling quality, but there are no guarantees. I’ll buy the heaviest one and take my chances. By doing this, I generally get 3-5 years out of these cheap tin boxes. But keep in mind I use the $20 cheapies in machines that spend their lives running a word processor and social media sites. I learned sometime in the 90s that putting $20 cheapie power supplies in gaming rigs is a bad idea.
These bargain-basement power supplies can be fine for basic PCs. Just don’t expect too much from them to avoid problems, and don’t expect to get a decade out of them.
The $35-$50 range: 500 watts
At the $35-$50 range, some ordinarily reliable power supply brands struggle to deliver much more quality than you’ll find in the $20 junk pile. Usually a $35 power supply is better than a $20 power supply, but I’ve had more problems with $35 power supplies than I have with my cheapies.
Generally speaking, Antec, Cooler Master, and Corsair sell good stuff, but not everything they sell at this price point is good. If the online reviews for whatever they have in this price range at this moment aren’t good, buy a different brand.
When it comes to ordinarily reliable power supply brands, I have done well with EVGA, Seasonic, and Thermaltake power supplies in this price range.
If you’re buying in person, the weight rule still applies here. If the Seasonic weighs more than the Thermaltake but the specs are about the same and the price is the same, I’ll buy the Seasonic.
Here’s a good rule in this price range: If you have to spend $5 more to get something that gets good reviews from other users, do it. If that better rated box has a lower efficiency rating and costs more, buy it anyway. I bought comparable power supplies from Thermaltake and Corsair in 2011. The Thermaltake was more expensive and less efficient. But the Thermaltake worked right out of the box and still works today like the day I bought it. The Corsair was DOA, and its replacement lasted about five years. Now, five years isn’t a bad run, but six years with no hassles is a better run.
Reliable power supply brands over $50
Once you get over $50, there are plenty of reliable power supply brands to choose from. You can pretty much go with any of the top-tier brands: Antec, Cooler Master, Corsair, EVGA, Seasonic, and Thermaltake will be fine. At this price point, get a good brand with adequate wattage, and use efficiency and modularity as the differentiators to help you make your final decision.
Getting 50-100 watts more wattage than the calculator says you need is fine, but overdoing it is a waste of money. There’s no reason to buy a 1,200-watt power supply when the calculator says 650 watts is enough. Running a power supply a little bit under spec increases life expectancy, but when you run too far under spec, you lose efficiency. You also pay a significant premium for the extra wattage, so shopping carefully pays off.
Modular cables are a nice differentiator. You can unplug any cables you aren’t using, so they aren’t taking up space and blocking airflow. You’ll end up with better airflow and a longer-lasting computer. You’ll also find the computer easier to upgrade since you’re not wrestling unused cables. Stash the unused cables in an empty drive bay in case you ever need them.
And if you buy a 600-watt or higher power supply, make sure it comes with a 16 AWG power cord. At that wattage, you need the thicker cord.
David Farquhar is a computer security professional, entrepreneur, and author. He started his career as a part-time computer technician in 1994, worked his way up to system administrator by 1997, and has specialized in vulnerability management since 2013. He invests in real estate on the side and his hobbies include O gauge trains, baseball cards, and retro computers and video games. A University of Missouri graduate, he holds CISSP and Security+ certifications. He lives in St. Louis with his family.
If you are getting a replacement for a working power supply, use a kill-a-watt on the computer and that will tell you exactly how much power it’s actually using.
In 90% of cases, a computer less than 10 years old with integrated graphics and a single hard drive will use less than 40 watts at idle and less than 100 at full load. The same system will a good but not ridiculous gaming card will use about 300 watts at full load.
As a rule of thumb, a 300 watt power supply will be more than adequate for any non-gaming computer, and a 400 watt power supply will be enough for all but the most beastly of gaming rigs. Unless you are putting in multiple gaming cards, it’s really hard to justify buying more than a 500 watt power supply, and even most gamers will be fine with 400 watts.
I learned long ago to use a white-out pen and write the date of installation on the PSU. Power degrades over time.