Seasonic M12D 750w ATX PSU

Cables & Internal Layout

Cables & Internal Layout

'Hybrid modular' is the name of the game on the M12D with the bare minimum cables required to get your PC up and running being already hard-wired into the unit. This has the advantage of providing some of the most important cables (ATX/EPS/PCI-E) with a direct connection to the PSU's power while also removing the potential for any dodgy modular connectors to add resistance to the circuit. It does however come at the cost of the PSU not being fully customisable by the user.

Seasonic M12D 750w Hard wired Seasonic M12D 750w hard wired

In the case of the 750w model Seasonic have hard wired  1x ATX, 1x EPS12v, 1x P4-12v, 2x PCI-E and 3x SATA connectors to the unit. Both the ATX 24-Pin and PCI-E 8-Pin connectors can be reduced down to 20-Pin and 6-Pin connectors respectively to support a wide range of motherboards and graphics cards, whereas the EPS12v 8-Pin connector is not interchangeable and for this reason Seasonic have included a separate 4-Pin P4-12v connector for older motherboards.

Seasonic M12D Main Cables Seasonic M12D PCi-E

A total of 8 modular cables are included, which is plenty for a modular system that can only support up to six cables being plugged in at any one time. Of course two of these connectors are dedicated to PCI-E only, which means that...yes, unlike the OCZ Fatal1ty 700w I reviewed last week...the M12D can support high-end dual graphics card configurations.

Seasonic M12D 750w Cables Seasonic M12D 750w Cables
Moving on to the more juicy stuff, removing the lid of the M12D reveals a reasonably tidy internal layout with two massive aluminium heatsinks running in parallel along the length of the unit. Hidden beneath the heatsink at the lower part of the picture (below-left) are several inductor coils that perform the PSU's PFC and AC transient filtering. The heatsink towards the top of the picture also hides some goodies; namely the +3.3/5.0v voltage regulation module and the huge bunch of cables that enter the unit.

Seasonic M12D 750w Inside Seasonic M12D 750w Heatsink

Seasonic M12D 750w Inside Seasonic M12D 750w Side
Two transformers take centre stage in the unit with the larger of the two responsible for the +12v rail, and the smaller being soley responsible for the 5vsb (standby voltage) rail. Over to the right of these are two large capacitors manufactured by Japanese company Nipon-Chemicon. The transformers carry specification markings of 400v / 390uF / 105c which shows that Seasonic haven't skimped on quality.

Seasonic M12D Trasnformers Seasonic M12D 750w Capacitors

The Sanyo Denki San Ace 120mm fan carries a model number of 9S1212H403, and despite details being pretty thin on the ground when I did a search of google, it appears to be capable of pushing 83CFM at <36dbA. Observant  people may have also seen the fan is actually fitted with a sheet of clear plastic on the exhaust side. This is probably to deflect airflow, making better use of air that would have normally exited straight out the back of the PSU.

Seasonic M12D 750w Fan Seasonic M12D Fan
Now let's pop the lid back on and get down to some testing...
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Most Recent Comments

21-03-2009, 07:58:31

Nice review m8. Bit on the pricey side for a 750w though imo.Quote

21-03-2009, 08:14:26

Originally Posted by name='w3bbo'
Nice review m8. Bit on the pricey side for a 750w though imo.
Agreed. Though with 90% efficiency you might get your money back in...oooh...50 years Quote

21-03-2009, 09:13:34

Got 2x 600w M12 over a year ago for around £100 each bundled with some icybox external caddies (that I sold on for about £20).

They're good enough units. Neither of them liked doing a 8 pin pcie adapter for a gtx280 tho, wouldn't even start it. Had to use a 500w pc&p.

I'm happy to see they've changed the modular banks to reflect 2x 8 pins in this model, as the majority of us would realize, it should be 'capable' of 4x 8 pin pcie (even with 2x adapters) - it would have been interesting if it would work considering my previous experience.

I'd like to see more variety in the ability to customize modular connections as a result.

Classic review once again, £150 is quite steep tbh.Quote

21-03-2009, 09:15:01

Dare I say it...needs more be competitive.

Although having said that 1kw is OTT for most systems.Quote

21-03-2009, 10:55:58

Originally Posted by name='w3bbo'
Dare I say it...needs more be competitive.

Although having said that 1kw is OTT for most systems.
Yeah I think Seasonic's take on this PSU was "You dont need 1KW, so lets spend the money on good components and performance elsewhere".Quote

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