Everyone roughly knows what these acronyms — CPU, RAM, SSD — mean, but the Power Supply Unit (PSU) is sometimes an afterthought when it comes to a new PC.
We're all suckers for the fastest processor, the mostest RAM, and the biggest HDD/SSD, but I'm telling you now that the PSU is the one thing you should first plan for.
The beating heart of a computer, the PSU is the component that delivers all the electricity your PC needs to work. While it must be said that everything's almost a single point of failure in a computer, a PSU that's malfunctioning can also short out your other components.
So if you're now convinced you should spend on a PSU, what should you get?
For starters, you'll need to look at the PSU's rating -- it's a measure of the component's efficiency under load. A PSU with an 80 Plus rating (which is the standard these days) means it is at least 80 per cent efficient when at full load. However, this does mean it will need to draw more power to reach max output.
Basically, a 500W 80 Plus will need 625W to deliver 500W of constant power (500/0.8). The more efficient it is, the less electricity is wasted and turned into heat.
The efficiency of the PSU increases depending on its rating: Bronze (82%), Silver (85%), Gold (87%), Platinum (89%), and Titanium (94%) on full load. The efficiency for each rating can also change at 50% load, and if you're interested to find out the exact numbers, head here.
For those on a budget, get Bronze. Silver rated PSUs are normally fine, but Gold PSUs are the sweet spot between price and performance. Anything higher is usually pretty expensive, since the PSU's internal parts will be of a better quality and cost more.
Now that that's out of the way, how much of a wattage should you get? A 550W PSU was good enough two years ago, but the new Nvidia and AMD cards, paired with your choice of processors, means it's not.
So here's a quick breakdown. While this is a rough guide, Asus has a handy online calculator (it's missing the newer graphic cards) if you want exact specific calculations. And look here for a chart with the newer Nvidia cards.
For the top of the line GeForce RTX 3090 paired with the powerful Intel HEDT or AMD ThreadRipper, don't settle for anything less than a 1,000W PSU. The requirements go down, up to 750W with an Intel i5 or AMD Ryzen5. The RTX 3080 has a base requirement of 750W, so a minimum of 850W is needed for the most powerful processors.
The RTX 3070 will need an 850W PSU for the fastest processor, or down to just 650W for an Intel i5 or AMD Ryzen 5. Meanwhile, the RTX 3060 Ti and 12G are more forgiving — you can get away with just 550W for the lowest end processor, and 750W for the top of the line chips.
As for AMD's Radeon RX 6000 series graphic cards, AMD makes it easy by suggesting at least an 850W PSU for the RX 6900 XT, 750W PSU for the RX 6800 XT, and 650W PSU for the RX 6800. I suggest getting just a bit more if you're running a higher-end processor as well, just to be on the safe side.
Lastly, if you have a bit more budget, it's always a good idea to go over the minimum. You'll never know if your next big upgrade will need a bit more juice, and PSUs tend to last a long time between upgrades -- I've only changed my PSU in about 6 years since I bought a pretty good 800W earlier on.
Aloysius Low is an ex-CNET editor with more than 15 years of experience. He's really into cats and is currently reviewing products at canbuyornot.com