Seasonic M12D 750w ATX PSU



OK so we've pulled the M12D apart, poked at it, put it through hell on our SM-268+ load tester and stuck it in a box hot enough to keep your roast dinner warm. But how did it perform?

Starting with efficiency the M12D 750w certainly did not disappoint. In almost all tests 88%+ was easily achieved by the unit with Test 2 (388w) even managing to hit 90%. I don't think I need to tell you how awesome this is as there are very few units on the market that can come close to this level of efficiency throughout every load level. The fact that the results remained steadfast inside our toasty 50°C hot box just further reinforces the point.

Although getting any official noise readings from the unit is quite difficult with all of the PSU testing equipment whirring away in the background, the M12D appeared to be completely inaudible until the loads levels of Test 3 (588w) were introduced; at which point the fan could just about be heard. Based on the relatively small number of PSU's I've tested with our new equipment so far (Corsair TX850w / OCZ Fatal1ty 700w / ASUS U-75HA) I'd say that the M12D is most certainly the quietest of the bunch.

Overall voltage stability was quite good with the +12v rails only shifting by 0.27v from Test1 to Test4 and similarly the +3.3v and +5v rails only shifting 0.16v respectively. Unfortunately the idle voltage levels were of a slight concern on the +12v rails, starting quite high at around 12.45v in Test 1. Although this is certainly within ATX spec and of no danger to damaging hardware, the mark of a quality PSU in my opinion at least is how close it can stay to 12.00v at all load levels.

Seasonic has responded to these results stating that they are uncharacteristic of this model. They have reproduced our load tests on their own equipment using an M12D from a different batch and the idle voltage levels are much lower. Due to time restraints we have been unable to obtain a different sample for testing, but should one become available in the future we will update this review with the revised results.

Finishing up with the scope output it's getting quite hard not to repeat everything I've said on the previous page. However, with the +3.3v and +5v rails staying below 11mV and the +12v below 43mV the results place this as one of the cleanest and greenest PSU's tested to date.

Coming in at £149.49 over at Scan, the M12D is at the high-end of what would be considered acceptable for a PSU of this wattage. In fact it would be short sighted not to point out the wide range of 800-1000w PSU's available for a similar price. However, while most of these can match the unit in some areas, the M12D represents a new breed of PSU that combines super-high efficiency with all the additional qualities of a top-end PSU. So for some, the additional outlay might be worth it in the long run.

The good
- Low ripple & noise on scope.
- Ultra high efficiency backed by 80PLUS Silver certification.
- Hot box testing produced near identical results to room temperature tests.
- Quality components - right down to the San Ace fan.
- 4x PCI-E connectors.
- 5yr Warranty.

The mediocre
- Average packaging for such an expensive PSU.
- Price quite high.
- Voltages on the +12v rails idle quite high.

The bad
- Nowt

Overclock3D Performance Award

Thanks to Seasonic for providing the M12D for review. Discuss this review in our forums.
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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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