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Seasonic S12G 450 W

Four 80 PLUS Gold Power Supplies Under 450 W, Reviewed
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In past round-ups, Seasonic fared well with its X family of power supplies. They're notably fully modular and equipped with dynamic fan control. Additionally, the company is known for its fantastic build and component quality.

But for this story, Seasonic sent us the 450 W version of its S12G. For a price right around $75, you get a compact, 80 PLUS Gold-certified PSU with completely fixed cabling. That makes the S12G the only power supply in our round-up without cable management. In return, a combination of sleeved, round cables and flat cables turn out to be the long side, giving you plenty of room for routing. Moreover, you get two auxiliary PCIe connectors and eight for SATA-based drives.

Surprisingly, Seasonic's build quality doesn't quite match up to the competition. Similarities we do find are a single +12 V rail rated for up to 37 A and five-year warranty coverage.

AC Input100-240 V, 50-60 Hz
DC Output+3.3 V+ 5 V+12 V (#1)+12 V (#2)+12 V (#3)+12 V (#4)-12 V+5 Vsb
20 A20 A37 An/an/an/a0.3 A2.5 A
Individual Output  32 A  3.6 W12.5 W
Rail UtilizationSysSysCPU & VGA
Combined Output100 W444 W
Total Continuous Output450 W
Peak Outputn/a

Seasonic’s X line is typically a top contender in our performance measurements. The less-expensive S12G still has something to prove, though. It does master our efficiency testing, according to the 80 PLUS specification, and even has a bit of room to spare.

At very low loads, the S12G’s efficiency is about the same as Corsair's RM450. At 25 W, it tails Cooler Master's V450S by about 10 percent. But in standby, without any load, Seasonic has the only PSU able to compete with the RM450 by demonstrating .05 W of consumption.

For those of you keeping score at home, that means this PSU hasn't exhibited any real weaknesses yet. The ripple and noise measurements continue along the same lines. There’s barely any ripple, and the curve is pretty smooth.

Thanks to its hybrid cooling solution, Corsair's RM450 just can’t be beaten when it comes to acoustics. Seasonic often triumphs in this metric. However, the company chooses not to use the dynamic cooling we've come to appreciate from its X family. That doesn't mean the S12G is loud. Quite the opposite. It's fan is on the quiet side, registering between 30.9 and 31.3 dB(A).

A Look at the PCB

There's no cable management, no hybrid fan control, and Seasonic sneaks in with the lowest price in today's story. Did the company have to cut some corners when it was picking components and putting the S12G together? Nope. We find a DC-to-DC converter topology with LLC, as well as a very good input filter including two X and six Y capacitors, three choke coils, and a MOV.

Hitachi supplies the primary capacitor. On the secondary side, there are a number of capacitors from the South Korean manufacturer Enesol, as well as a few by Chemi-Con and Rubycon. All in all, the parts are higher-quality than what we found from the other power supplies in our round-up. And then there’s the immaculate soldering work.

The bottom line is that Seasonic does everything right for a PSU in this price category for both component selection and build quality.

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