Seasonic M12D 750w ATX PSU


When it comes to silent yet powerful PSU’s, Seasonic are often one of the first companies to be mentioned. In business for almost 35 years, Seasonic certainly know what they are doing when it comes to manufacturing power supplies with some of their previous models having reached an almost iconic standing among the silent PC community.

However, despite Seasonic having a full range of retail PSU’s, some of which we’ve reviewed in the past, Seasonic’s primary business is in OEM – building PSU’s to spec for companies such as PCP&C and Corsair. Therefore, the release of their own models is often few and far between making the chance to review one an opportunity I’d certainly never pass up.

In case you hadn’t already guessed, today’s subject is going to be the M12D 750w. Released at the tail end of 2008 the M12D is a modular unit that builds on the features of the original M12 600w unit that I had the pleasure of reviewing just over two years ago. However, over the course of two years a lot has happened in the world of OC3D PSU testing and today the M12D is going to be facing a wrath of our SunMoon load tester combined with a toasty 50°C oven. But let’s not get ahead of ourselves and instead start off with some specs pulled from Seasonic’s website:

• Super High Efficiency (up to 90%) – Green solution for lowering energy consumption, noise & heat.
• DC to DC Converter Design – Superior dynamic response & greater system stability.
• Practical Dual +12V Rails – Ample +12V output with OCP for extreme utilisation.
• Tight Voltage Regulation – Improved load regulation to reduce voltage variations.
• Highly Reliable 105°C Japanese Brand Capacitors – Exceptionally reliable components extend product life.
• Solid Caps on 12Vs for Extreme Stress Operating Conditions – Enhanced stability at severe operating conditions.
• Active Power Factor Correction (99% PF) – Reduces line loss & power distortion.
• Dual Sided PCB Layout – Better utilisation of PCB space to enhance quality and performance.
• Detachable Modular Cables – Flexible cable solution to reduce clutter.
• San Ace Silent Fan (Sanyo Denki) – Premium quality fan for silent operation.
• Smart & Silent Fan Control (S2FC) – Smart thermal control to balance between noise & cooling.
• Ultra Ventilation (Honey Comb Structure) – Minimises airflow resistance for maximum cooling.
• Multi-GPU Technologies Supported – 6P and 8P PCI-E connectors to support all multi-GPU platforms.
• All-in-one DC Cabling Design – Supports PC, IPC, workstation, and server systems.
• Universal AC Input – Plug & run safely anywhere in the world.
• Patented Easy Swap Connector – Unplug the connectors easily, quickly, and safely.
• 5 Year Warranty – Our commitment to superior quality.

Aaaand breathe! Phew. Quite a long list of features there with Seasonic including everything from the shape of the ventilation mesh to the manufacturer of the cooling fan! But hey ho – if you’ve got it, flaunt it! Right?

Out of all the features the most prominent one of all has to be the 90% efficiency. Only a hand full of units out there at the moment can actually achieve this and it will certainly be interesting to see if we can get anywhere close to this during our testing. Other interesting points also have to be the Japanese 105°C caps and support for ‘all’ multi-gpu configurations; but I’ll have a closer look at those over on the next few pages.

Seasonic M12D 750W Rail Layout DC Output +3.3V +5V +12V1 +12V2 +12V3 +12V4 +12V5 +12V6 -12V +5VSB 24A 30A 36A 36A – – – – 0.8A 3A Max Power 150W 744W 9.6W 15W 750W

What a lovely pair……of +12v rails we have. Each with an individual maximum capacity of 36A and a combined max capacity of 744W (62A). Of course once you start placing load on the +3.3v and +5v rails, this eats into the +12v output somewhat (remember its ‘only’ 750W total), but for almost all mid to high end PC’s the configuration should be perfect.

Now lets move on to the next page where we take a look at the unit in all its glory..