Seasonic M12D 850W: DC-to-DC Perfection?
by Christoph Katzer on November 26, 2008 12:00 AM EST- Posted in
- Cases/Cooling/PSUs
Packaging and Appearance
The power supply comes in a nice package, enclosed by a bubble wrap bag. This is a modular power supply, so the extra cables come with a small bag that you can use to store the extras. You also get a manual and warranty card, which you will want to hang onto since this power supply comes with a five-year warranty.
This is another black power supply, which probably doesn't matter to most users. The power supply doesn't need to be painted at all, but somehow gray power supplies are no longer as desirable, so PSU companies have settled on black as the new standard. As always, the back is perforated to allow air to exhaust from the PSU, but there's a large Seasonic logo next to the AC jack that blocks some of the ventilation. This is nothing to worry about, however, as Seasonic placed the filtering stage right behind this area, shielded by copper plate that would have blocked airflow regardless.
Compared to some competing power supplies, the 120mm fan looks a little small -- lately we've seen 130 and 140mm fans that take up the entire bottom of the PSU. We will look at cooling and noise performance later to see if that makes a difference. The front of the PSU has six sockets for peripheral cable harnesses and two PEG harnesses. As a whole, the PSUs looks very sleek and displays great craftsmanship, which is nothing less than we would expect from Seasonic.
We took the fan grille off and power up the PSU so that you could see what's directly below the fan. We felt the fins on the heatsinks were a little too big, but Seasonic assures us the size was calculated for optimal performance. It's still better than what we've seen with CWT built models, where the fins block most of the airflow resulting in components that often get hotter than necessary. Seasonic leaves plenty of space between the wide fins, so airflow to the components below will not be a problem. Looking at the above image, you can also see that both the primary and secondary heatsinks will get plenty of airflow, so cooling should be very good.
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CEO Ballmer - Saturday, November 29, 2008 - link
I have one, works nicely!http://fakesteveballmer.blogspot.com">http://fakesteveballmer.blogspot.com
InterClaw - Friday, November 28, 2008 - link
How much power does the M12D consume while in standby mode (switch on) running on 230Vac?Christoph Katzer - Saturday, November 29, 2008 - link
I will have a small update on that because I did some further testing. The M12D has an incredible high sb-efficiency with up to 76% which is really good compared to 40-ish% of many others.daar - Wednesday, November 26, 2008 - link
Can someone explain the significance for the DC-to-DC configuration over what they or other PSU manufacturers normally do? I mean other than the odd efficiency curves, it doesn't really provide anything unique when compared to say, the Enermax.PrinceGaz - Wednesday, November 26, 2008 - link
I'm guessing here and haven't checked my "facts", but I'm guessing the DC-DC conversion helps because it allows the PSU manufacturer to concentrate most of their effort on providing a clean and efficient +12V rail from the AC supply, then tag the conversion circuitry onto the end of that to generate the less critical +5V and +3.3V rails.The alternative is to have seperate circuitry for generating +12V, +5V, and +3.3V all individually from the AC supply.
JarredWalton - Thursday, November 27, 2008 - link
I believe that's right - it's easier to do 12V DC to 3.3V/5V DC than it is to do 120V/230V AC to the same, so you do one good AC-to-DC conversion and then a couple simpler DC-to-DC conversions.mindless1 - Saturday, November 29, 2008 - link
It's not necessarily easier, it's just that if you first convert to 12V alone you have maximized the amount of 12V current a single transformer of a given size can produce, then let that be the primary feedback voltage to determine switching pulse width. That typically also means you can have higher ratios of 12V to 5V or 3.3V current without going out of spec. It makes more and more sense to do so when a PSU is of high wattage as it's then expected to have so much more 12V current consumption as a % of total power used.Mr Perfect - Wednesday, November 26, 2008 - link
Maybe you could put a bug in Seasonic's ear about their "little" 120mm fan? Looking at the acoustic results, you can't help but wonder what a 140mm fan could have done for that curve. A 140mm might have shifted the whole curve down two or three decibels.piroroadkill - Thursday, November 27, 2008 - link
Bear in mind half of the fan is usually covered towards the front of the PSU, I'm really not sure a 140mm fan helps at all, because that's simply more airflow that's blocked by a baffle. This baffles me (hurr)... Seems like 120mm is perfectly adequete, and more to the point, if you so wish to change the fan yourself, at least 120mm is a standard sizeMr Perfect - Thursday, November 27, 2008 - link
140s are mainly interesting because they produce any given amount of airflow at a lower RPM then 120s. So rather then run it at the same RPM as the 120, and just block more airflow, they could run it at a lower RPM while producing the same airflow. Then maybe it would top out around 28DB instead of a 31DB, or idle at 15db instead of 17. Hopefully there wouldn't be a need to change the fan then.