Your PC's power supply / PSU plays a big role in determining your system's reliability, depending on its performance. So you should be careful when it comes to picking the right PSU for your system. The best power supply should also have features to save your system's parts (including the power supply itself), in case something goes wrong with your electricity supply or other components. If it doesn't, it's clearly not the best power supply and is putting your other expensive PC parts at risk.
You'll also have different concerns, of course, depending on whether your power supply will be pushing a monster mining rig, an always-churning workstation, or a basic productivity or gaming PC. We’ll help you find the best power supply for your next desktop PC below.
Quick Power Supply Shopping Tips
First, figure out your wattage requirements. You don't need to purchase much more potential power capacity (wattage) than you’ll ever use. You can calculate roughly how much power your new or upgraded system will draw from the wall and look for a capacity point that satisfies your demands. Several power supply sellers have calculators that will give you a rough estimate of your system's power needs. You can find a few below:
- Cooler Master Power Calculator
- Seasonic Wattage Calculator
- MSI PSU Calculator
- be quiet! PSU Calculator
- Newegg PSU Calculator
You probably don’t need a 1,000-watt PSU, even for an extreme gaming rig. A few years ago, all graphics cards on the high-end of our GPU Benchmarks hierarchy were very power hungry. But this has changed with Nvidia's recent architectures. It's simply not necessary to buy a 1kW PSU for a couple of RTX 2080s. An 800W model will do just fine, leaving headroom for an overclocked CPU as well, as you can see in our CPU Benchmarks hierarchy. Fans of AMD's high-end Radeon VII or the newer Radeon RX 5700 XT will need to plan for higher power use, pairing these cards with PSUs featuring greater maximum output.
Check the physical dimensions of your case before buying. If you have a standard ATX PC case, chances are an ATX power supply will fit. But many higher-wattage PSUs are longer than the typical 5.5 inches. So you’ll want to be sure of your case’s PSU clearance. If you have a particularly tiny or slim PC case, it may require a less-typical (and more compact) SFX power supply. We have picks for this form factor below as well.
For more on this subject, see our A Basic Guide To Motherboard, Case and Power Supply Form Factors feature.
Want a clean build or working in a tiny case? Consider a modular power supply. If your case has lots of room behind the motherboard, or your chassis doesn’t have a window or glass side, you can of course cable-wrap the wires you don’t need and stash them inside your rig. But if the system you’re building doesn’t have space for this, or there’s no easy place to hide your cable mess, it’s worth paying extra for a modular power supply. Modular PSUs let you only plug in the power cables you need and leave the rest in the box.
The Best Power Supplies You Can Buy Today
Of the two variants of Corsair's CX450, the Great Wall version is more efficient than CWT's, especially under light loads, and has a more efficient 5VSB rail. On the other side, it has a more-aggressive fan profile, so its noise output is increased. In the US market, you will only find the CWT version, which is made in Vietnam instead of China, so it avoids the tariffs and keeps its price tag low.
Read: Corsair CX450 Review
Alternate Best Cheap Power Supply: Corsair VS450
Another decent alternative if your budget is low, you need more than 500W of capacity, and you aren't that concerned about efficiency or some fan noise under load is the Corsair VS650. It won't win any performance awards, but it gets the job done without much in the way of frills or fuss, for less than $50. You may also be able to save on these or other PSUs by checking Corsair coupon codes.
The smallest member of the new RMx line gets updated with a top-notch magnetic levitation fan which doesn’t affect the overall noise output, so the new RM550x is one of the quietest PSUs in the 550W category. It would be nice if Corsair added a second EPS connector in this unit, but most folks will be more than satisfied with the connection options.
Read: Corsair RM550x Review
Alternate Best PSU 550W: Phanteks AMP Series 550W
The XPG Core Reactor with 650W max power can achieve higher overall performance than the two hottest picks in this category, the Corsair RM650x, and the Seasonic Focus Plus Gold, with similar capacity. It also has a silent operation, thanks to the relaxed fan profile, despite its compact dimensions. The build quality is high, and the provided warranty meets the competition's offerings. Finally, the two EPS connectors provide compatibility with the high-end mainboard, but they should be installed on dedicated cables—all in all, an excellent power supply.
Read: XPG Core Reactor 650W PSU Review
Alternate Best PSU 650W: Thermaltake Toughpower PF1 650W
It wasn't easy to deliver a better product than the existing RM750x (2018), but Corsair managed to do this, and the new model achieves notably better performance. Compared to the previous model, it loses in quietness, but you cannot call it noisy with 28 dBA overall noise output. All in all, this is an excellent power supply, leading the 750W Gold category.
Read: Corsair RM750x (2021) PSU Review
Alternate Best PSU 750W: XPG Core Reactor 750
If you need the best 850W power supply and you don't have a restrictive budget, the AX850 should be among your top choices. It registers high performance in all areas: efficiency, load regulation, ripple suppression, transient response and, on top of that, it is dead silent as well.
While it's the best 850 watt premium PSU around, it's not a perfect device. I wish the current triggering points on the minor rails were lower, that there was a larger distance between the peripheral connectors (ideally 150mm) and that there were 16AWG gauges on the EPS connectors.
Read: Corsair AX850 Review
Alternate Best PSU 850W: XPG Core Reactor 850W
Corsair's AX1000 is one of the best 1kW power supplies available. If you want the highest possible performance matched with quiet operation, don't hesitate to make it the centerpiece of your next build (provided the price doesn't scare you off).
This beastly PSU offers tight load regulation on all of its rails, amazing ripple suppression, and crazy-high efficiency levels. Its transient response is impressive, so we're not surprised that it takes the lead from Seasonic's 1000W 80 PLUS Platinum- and Titanium-rated models (even though they're built using the same platform with slight modifications).
Read: Corsair AX1000 Review
Alternate Best PSU 1K Watts: Thermaltake Toughpower Grand RGB 1200W
If you want silent operation and high-power output, the be quiet! Dark Power Pro 12 with 1500W max power fits the bill. It sports extremely high build quality and its semi-digital platform, offers top performance and can handle high operating temperatures. The only problem is the high price, but in systems that require this much power, the power supply is usually among the least-expensive parts when compared to the installed CPUs and GPUs.
Read: be quiet! Dark Power Pro 12 1500W Power Supply Review
We waited years for a competitor to dethrone Corsair's AX1500i, and in the end it was another Corsair power supply to post higher overall performance. The Corsair AX1600i is the best PSU that money can buy today, period. It offers top performance in all areas and uses an innovative platform, which provides a glimpse at the future of power supply design.
The use of a cutting-edge PFC circuit in combination with a fully digital platform seems to be the key for record-setting performance. Besides its super efficiency, the AX1600i also offers great load regulation, amazing transient response, a long hold-up time, and unparalleled ripple suppression. Moreover, the great benchmark results are accompanied by quiet operation, enabled by a relaxed fan profile and a high-quality FDB fan. Using the Corsair Link software, you're able to choose between three fan modes: performance, balanced, and quiet.
Read: Corsair AX1600i Review
Alternate Best PSU Above 1500 Watts: SilverStone DA1650 Review
The Corsair SF750 is the strongest and one of the best SFX power supplies that money can get you today. If you want so much power out of such a small PSU and you can afford its stiff price, there is no other option. It can easily support a potent gaming system and thanks to the couple of EPS connectors that it has, and is compatible with high-end mainboards that need more juice in the CPU's area.
If you don't need more than one graphics card connector, you should consider the top-notch SF600 Platinum instead and save yourself some serious money. Corsair has set the so high in the SFX market that even SFX pioneer SilverStone, doesn't have, for the moment at least, a competing 750W SFX model in its portfolio.
Read: Corsair SF750 Review
Alternate Best SFX Power Supply: Corsair SF600 Platinum
Fractal Design's Ion SFX (-L) model with 650W max power offers high performance, highly flexible modular cables, and compact dimensions at a reasonable price. If only its fan speed profile was a bit more relaxed.
Read: Fractal Design Ion SFX Gold Review
Alternate Best SFX-L Power Supply: SilverStone NJ450-SXL
Finding Discounts on the Best Power Supplies
Whether you're shopping for one of the best power supplies or just looking for an affordable alternative, you may find savings by checking out our lists of the latest Corsair coupon codes, Newegg promo codes and Micro Center coupons.