Seasonic M12D 750 W (SS-750EM) was one of the best-performing power supplies we’ve reviewed to date, presenting only high-end components and a very high efficiency thanks to the DC-DC converter used on its secondary. Seasonic released now a more affordable version from this power supply, called S12D (SS-750HT), which the main difference is not coming with a modular cabling system. Let’s see if this is the only difference between them.

As you may be aware, Seasonic is a traditional OEM manufacturer, being the real manufacturer behind units from brands like Antec, Corsair and Arctic Cooling (not all power supplies from these brands are manufactured by Seasonic, though). One annoying thing about Seasonic is that they have three websites,, and, but retail products like the reviewed power supply can only be found on the later. In our opinion this makes no sense and only makes it difficult to consumers to find out more about their products.

Seasonic S12D 750 W power supplyFigure 1: Seasonic S12D 750 W power supply.

Seasonic S12D 750 W power supplyFigure 2: Seasonic S12D 750 W power supply.

S12D 750 W isn’t a long power supply, being 6 19/64” (160 mm) deep, using a 120 mm fan on its bottom and featuring active PFC, of course. As mentioned S12D doesn’t have a modular cabling, and all cables have a nylon protection that comes from inside the unit.

This power supply comes with the following cables:

  • Main motherboard cable with a 20/24-pin connector.
  • One cable with two ATX12V connectors that together form an EPS12V connector.
  • One cable with one EPS12V connector.
  • Two cables with one six-pin auxiliary power connector for video cards each.
  • Two cables with one six/eight-pin auxiliary power connector for video cards each.
  • Three cables with three SATA power connectors each.
  • One cable with three standard peripheral power connectors and one floppy disk drive power connector.
  • One cable with three standard peripheral power connectors.
  • One adapter for converting one standard peripheral power connector into two floppy disk drive power connectors.

Each cable has a different length. The main motherboard cable is 20 ½” (52 cm) long, the ATX12V/EPS12V cables are 22” (56 cm) long, the video card cables are 22.5” (57 cm) long and the SATA and peripheral cables have 16 1/8” (41 cm) between the power supply housing and the first connector on the cable, and then 5 7/8” (15 cm) between the connectors, except on the peripheral cable with the floppy disk drive connector, where the distance between connectors is of 4 3/4”(12 cm).

All cables use 18 AWG wires. There is a small difference between S12D and M12D here: M12D use thicker 16 AWG wires on the main motherboard cable and on the video card auxiliary power cables.

Seasonic S12D 750 W power supplyFigure 3: Cables.

The number of cables is terrific for the high-end user, however if you want to install more than two very high-end video cards you will need to use adapters, since each very high-end card takes two auxiliary power connectors each and this power supply comes with “only” four of them.

Now let’s take an in-depth look inside this power supply.


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.