Seasonic M12D SS-850W PSU

Part Modular, Mostly Black

Seasonic's achingly regular design eschews in yet another matt black power supply into a world of matt black power supplies.

Part of me realises that Seasonic won't change a winning formula and a subtle design usually heeds a winning vote from many potential customers, but the other half relishes something a bit different that stands out from the usual "sexy hardware" like graphics cards. When I say this, I'm referring to something like Cooler Master's military ruggedized UCP 900W PSU, although it quite rightly avoids the frequently used bling lights that some companies think help to add value.

The black box surrounds other black hardware like the fan, the modular connectors and the fan grill too, although the heatsinks inside are plain aluminium if you care to look that hard. The only embellishment is from the Seasonic sticker in the centre of the fan grill and one side has Seasonic's power rating sticker.


The cable braiding goes neatly into the PSU which is a definite plus, while the modular connectors are nice and tidy. We're very thankful to Seasonic for redoing its modular connectors - the old ones were terrible to use because you could never get your finger between them to unplug the connector. This is now no longer a problem, as all the clips are easily accessible on one side - it's a better solution than the Antec Signature 850W's, although while not colour coded they are easily identified by the varying size of connectors (eight versus six) and labels underneath.


The semi-modular approach is a popular one for this type of premium PSU with necessary cables like the ATX, EPS12V and a few PCI-Express connectors sprouting from the actual unit, then extra PCI-Express and the peripheral connectors included as optional extras. This has been decided as the best of both worlds approach, with some of the key hardware cables not suffering from a potential voltage drop a modular connector can create, while still maintaining some degree of flexibility.

Seasonic uses a dual 12V rail design, although they both stem from the same, single 12V source but for 850W in total they can provide a whopping 840W of this - or nearly 99 percent. This essentially enables virtually any combination of 3.3V/5V or 12V a modern system might demand. The 840W means "only" 70Amps out of the potential 40+40Amps that can be provided, but this does allow for some degree of flexibility from a multi-rail design.