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Power supplies
Buying a good power supply for your new PC is a must. Cheap PSUs can cause all kinds of problems, from poor stability to premature component failures. Also, many cheap units deceive with inflated wattage ratings. For example, a "500W" bargain-bin PSU might get half of its rating from the 5V rail, which is relatively unimportant, leaving only 250W for the 12V rail, which supplies power-hungry components like the CPU and GPU. In contrast, quality PSUs derive most of their wattage ratings from the capacity of their 12V rails. That means an el-cheapo 500W unit could be less powerful in practice than a quality 350W PSU.

The power supplies we've singled out below are quality units from trustworthy manufacturers who offer at least three years of warranty coverage. Past editions of the System Guide have featured modular PSUs exclusively, but we've changed our thinking on that topic, at least at the budget level. Although modular cabling certainly helps to keep the inside of a PC less cluttered, the benefits are largely cosmetic. Folks without windowed cases may not need modular cables, and others may not be able to afford the perk.

At the same wattage, higher-quality PSUs with non-modular cables can often be had for only a little more money than lower-quality alternatives. While modular cabling is still a consideration, we've included some non-modular recommendations that trade convenience for better internal components and longer warranties.

We also tried to find PSUs with 80 Plus Bronze or better certification. 80 Plus Bronze guarantees efficiency of 82-85%, depending on the load. The higher a PSU's efficiency, the less energy it turns into heat while converting AC to DC power, and the easier it is to cool quietly. 80 Plus Bronze, Silver, or Gold units tend to have large, slow-spinning fans that are barely audible during normal use. They'll save you a bit of money on your power bill over the long run, too.

Budget

Product Price Notes
Seasonic S12II 430B $41.90 Non-modular, one 6+2-pin PCIe power connector,
one six-pin PCIe power connector
Corsair CX450M $49.99 Semi-modular, two 8-pin PCIe power connectors

For entry-level systems, we're recommending the Seasonic S12II 430B this time around. This 80 Plus Bronze unit has a 120-mm fan and a five-year warranty. It offers one six-pin and one eight-pin PCIe power connector. Entry-level and midrange graphics cards often need just one auxiliary connection from the PSU these days (if they require external power at all), so the S12II 430B should be more than enough PSU for budget boxes. Seasonic covers the S12II 430B with a five-year warranty, too.

If you'd rather have an affordable modular PSU, you can't really go wrong with one of Corsair's latest, the CX450M. Corsair tells us this CX450M, along with its 550W and 650W brethren, uses DC-to-DC conversion on its +3.3V and +5V rails to attain compatibility with newer Intel CPUs' low-power sleep states. This unit's semi-modular cabling could make for cleaner builds than the non-modular Seasonic above. 

Sweet spot

Product Price Notes
EVGA Supernova 650 G2 $89.99 Semi-modular, two 6+2-pin PCIe connectors
EVGA Supernova 750 G2 $99.99 Fully modular
four 6+2-pin PCIe connectors,
semi-silent mode
Corsair RM750x $109.99 Fully modular, single 12V rail,
six 6+2-pin PCIe connectors, 10 SATA connectors,
semi-silent mode

PSUs aspiring to the Sweet Spot need to do more than the basics. We demand semi-modular cabling here at the bare minimum. 80 Plus Gold efficiency ratings should ideally be on the table, as well, along with semi-silent fans that spin down completely under lighter loads.

It's worth mentioning that PSU pricing in the 80 Plus Gold arena is a little weird lately. Prices for units roughly between 550W and 650W are quite high compared to their higher-capacity brethren at 750W and 850W. Our choices above take this fact into account. You'll also be forgiven for think we're overspeccing power supplies, given that modern systems with a single graphics card have trouble breaking 450W of consumption or so. We're picking higher-capacity units as a hedge against capacitor aging. There's nothing like the warm fuzzy feeling you'll get ten years from now when you're still running the same PSU you bought today.

For systems that need more than the units in our budget range can supply, we'll start with the EVGA Supernova 650 G2. This high-quality PSU has an 80 Plus Gold rating, fully modular cabling, and enough oomph (and plugs) to power graphics cards with multiple PCIe connectors. At $90, it's a pretty good deal, and EVGA sweetens it further with a whopping 10-year warranty.

If you need even more power for lots of hard drives or basic multi-GPU configurations, EVGA's Supernova 750 G2 fits the bill. EVGA's confidence in the unit shows once again with a 10-year warranty. Beware, though: without registration, the warranty coverage only lasts three years.

On the upper end of the Sweet Spot, we have the Corsair RM750x, a recent entrant in our Guides. Our recent personal experiences with Corsair's RM range has left us with nothing but good impressions, and what's good for us is good for you folks too. The RM750x is a beast of a PSU with an enormous, quiet fan, and should be able to handle anything you care to throw at it—even dual-card setups. Corsair offers 10-year warranty coverage on the RM750x, too.

High end

Product Price Notes
Corsair RM850x $119.99 Fully modular,
six 6+2-pin PCIe connectors, 10 SATA connectors,
semi-silent mode, C-Link monitoring
EVGA SuperNova 850 P2 $149.99 Fully modular,
four 6+2-pin & two 6-pin PCIe connectors,
10 SATA connectors, semi-silent mode

Corsair continues its resurgence in our Guides with the RM850x. This unit is similar to the RM750x model above, but with a little more punch. We've even run a Core i7-6950X and three GTX 1080s at full tilt off this unit with nary a peep or complaint. If you're looking for a powerful unit that won't break the bank, this is it.

The prices on 80 Plus Platinum PSUs have come out of the stratosphere recently. Given that development, we're recommending EVGA's SuperNova 850 P2 as another foundation for the most power-hungry systems builders might want to put together. This highly-efficient PSU offers semi-silent operation and more than enough power cables to run multiple graphics cards. This unit should last you a good long while, and the company offers 10-year warranty coverage.