Gamers all over the world are clamouring to get their hands on the latest and greatest graphics cards from Nvidia and AMD, but with the biggest generational leaps in performance we’ve seen yet – and I’m paraphrasing Spielberg’s shark epic here – you’re gonna need a bigger power supply. Knowing which one to choose to feed these hungry beasts is a job in itself, but be quiet! is here to shed some light on the right PSU for you.
Graphics cards are the biggest power guzzlers in your PC, so it’s no surprise that these new GPUs are slamming their fist on the table, demanding more wattage like a Viking out of beer. Nvidia is currently recommending a 750W power supply for its flagship graphics cards, since the GeForce RTX 3090 consumes around 350 watts without factoring in the rest of your PC. AMD advises the same for its new Radeon RX 6000 line-up, with the top-end RX 6900 XT being the only exception, requiring a meaty 850W box to run without issue.
Knowing what wattage to go for is just the tip of the iceberg, however, as there’s a lot more that goes on under the hood. Is a Gold Plus-rated power supply better than an unrated? What about a single- versus multi-rail? And what happens if you choose wrong?
A power supply works by converting the alternating current (AC) power from your mains to the direct current (DC) needed to feed your gaming PC. Your system will only draw the amount that’s needed, so your 750W power supply won’t be using all 750 watts if the sum of your components is just 600 watts. It doesn’t mean it’ll only draw 600 watts in this example, either, as no technology is 100% efficient and the conversion from AC to DC means some power is lost and a little more is required for headroom.
Most power supplies from reputable vendors at least conform to the bare minimum of an ’80 Plus’ rating, meaning you should get a minimum of 80% efficiency at 20%, 50%, and 100% load. The remaining 20% is considered waste that is generated into heat, which is why these boxes have fans attached to them. Straight out of the PC Olympics – if there were such a thing – there are more efficient power supplies you can pair with your shiny new graphics card, though.
PSU Efficiency | 20% Load | 50% Load | 100% Load |
80 Plus Bronze | 82% | 85% | 82% |
80 Plus Silver | 85% | 88% | 85% |
80 Plus Gold | 87% | 90% | 87% |
80 Plus Platinum | 90% | 92% | 89% |
80 Plus Titanium | 90% | 92% | 90% |
Going for Gold won’t necessarily make your gaming PC run any better, but with how much power these graphics cards eat, higher ratings can chip away at your electric bill. And, if nothing else, these stamps can sometimes be a great indicator of quality – although be quiet! gives its power supplies the same level of assurance across all ratings.
Choosing between a single-rail and multi-rail power supply, however, can make a big difference to your gaming PC’s performance. Both do what they say on the tin, with a single-rail pulling a larger amount of power across one individual rail to all components, while a multi-rail unit separates the power distribution across several rails, each catering to different components.
“PSU manufacturers spend a lot of time distributing the power draw of the different components you might install in your PSU reasonably between its 12V rails,” be quiet!’s Martin Pajenkamp explains. “For example, if you have four total rails, the first might be responsible to supply all drives and the motherboard with power, the second is reserved only for the CPU – to follow Intel’s request to provide an individual 12V rail just for the processor without interference – and the third and fourth are connected to the PCI Express slots.”
Since the new graphics cards have such a high demand and could possibly exceed the maximum amperage of one rail on a multi-rail layout, the knee-jerk reaction is to look at single-rail solutions instead. After all, single-rails have a reputation for being more stable and better for overclocking. Unfortunately, only the latter is true, and only if you’re an enthusiast looking to overclock using liquid nitrogen or liquid helium, otherwise a single-rail poses a greater risk to all your components if levels spike to the maximum amperage.
“Multi-rail power supply units make it easier to implement an effective Over Current Protection (OCP), because the total power on each rail is lower than the total power on the rail of a single-rail power supply unit,” Martin tells us. “Safety is the main reason why we almost exclusively use multi-rail for our power supplies. With multiple rails that are secured individually, it’s more likely the PSU will shut off if a component is displaying unusual behaviour, which might avoid damage to other components in the computer or, in the worst case, a cable fire. This becomes more important with higher wattage units. On top of that, the OCP tripping point for each rail is higher than the rated current that is shown on the PSU label, to provide some headroom for power spikes.”
So if a single-rail power supply poses a risk to your expensive new graphics card and the GPU might exceed the maximum amperage of its allocated rail a multi-rail model, which should you go for? A multi-rail power supply will always be your best bet, so long as it has the right features to support your gluttonous graphics card. be quiet!, for example, allows “at least one PCI Express connector” to draw power from two separate rails on its power supplies, feeding enough juice to your components while keeping them safe.
If you decide to make the jump to a new graphics card, it’s important to get a high wattage, consider the efficiency rating, and stick with multi-rail units. If your power supply doesn’t have enough power to, well, supply your GPU, you’ll be lucky if your PC boots and doesn’t randomly serve you a BSOD or multiple restarts, let alone be able to play games with high frames.
And whatever you do, don’t get a power supply just because it’s cheap. We’ve suffered short circuiting because of this mistake in the past and it can cost more money down the line if you have to replace broken parts as a result.
Thankfully, you shouldn’t have any of these problems if you get your hands on a high wattage be quiet! power supply – and true to its name, it keeps the decibels low. Make sure to visit the be quiet! website if you’re still shopping around and need more information.