Seasonic S12D 850W Power Supply Review

Installation and Use

I used OCCT Perestroika in conjunction with Speedfan for benchmarking and monitoring on Windows XP Pro 64-bit after installing into my standard testing rig with an ASUS M3A32-MVP motherboard, Phenom II 940, 8 GB of DDR2 RAM, three SATA hard drives, a Creative X-Fi gamer, and a Foxconn-made nVidia 8800 GTX.

Seasonic S12D 850W Power Supply
Spot checks put the 3.3V and 5V at 3.3V and 5.11V at both load and idle, and 12V rail at 12.1V idle and 12.04V load.

I’ve included graphs from the recent Corsair HX 750 review.

The 3.3V rail was stable throughout the test, barely rippling at all. Impressive.

Seasonic S12D 850W Power Supply Seasonic S12D 850W Power Supply
The 5V rail was likewise fairly stable. The ripple was slightly more than 0.50%, which is pretty much negligible.

Seasonic S12D 850W Power Supply Seasonic S12D 850W Power Supply
The 12V rail was the wild one of the bunch, and considering its ripple was only 0.01% more than the 5V rail, that’s not saying much.

Seasonic S12D 850W Power Supply Seasonic S12D 850W Power Supply
The noise level was undetectable beyond the ambient noise produced by my stock AMD cooler and Thermaltake DuOrb cooler for my video card.

Final Thoughts

This is one rock solid power supply. I’ve seen few PSUs as stable as this one. It may not look like much, but who cares? It’s a power supply. PSUs are generally hidden from view even inside windowed rigs. I think the biggest drawback to the S12D is the fact that it’s not a modular power supply. The medusa-like bush of power snakes is unattractive to most enthusiasts these days, but there are certainly some out there who would rather eke out every bit of efficiency and exercise their cable management skills at the same time.

While it’s not perfect, I do recommend this unit to those looking to build a multiprocessor system, as well. The S12D is likely among the strongest units for multisocket motherboards.

ThinkComputers gives the Seasonic S12D 850W power supply unit a 9 out of 10 score and our Editor’s Choice Award.

rating9 10 small TC award editorschoice small


– Quick release/easy insert device connectors
– Quiet fan
– Impressive stability
– Supplies just the right amount of power


– Pricier than some competitors’
– Cables aren’t well protected as they come out of the unit
– Not modular

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