Seasonic X900 SS-900HP 900w PSU

Internals & Cables

Internal Components

In the past, many people have judged the quality of a PSU on its weight and size of internal components. However, with many manufacturers moving on to newer and more efficient ways of designing their PSU's, it has become increasingly obvious that this is no longer a reliable method for gauging a power supply's quality. By looking inside the X900 we should be able to identify some of the components used and get a good feel for the overall build quality of the unit.

Seasonic X900 Insides

On opening the X900 the first thing that stands out is the large aluminium heatsinks responsible for cooling the the two banks of mosfets attached to them. Sandwiched between the heatsinks are two transformers and a capacitor. The larger of the two transformers (left) is most likely responsible for the +12v rails, with the smaller transformer (upper-right) responsible for both the +3.3v and +5v rails. At the centre is a large black capacitor manufactured by Japanese company Nippon Chemi-con.

Seasonic X900 Inside Seasonic X900 Inside

The overall layout of the X900 is fairly spacious, with plenty of room between the 80mm fan and component board to prevent any cooling dead spots. The aluminium heatsinks are finned in a way that aids the flow of air through the unit and all cables are bundled together with zip ties, giving the inside of the unit a very tidy appearance.

Seasonic X900 Fan

With many PSU manufacturers designing their latest models with 120mm fans it seems rather strange why Seasonic, a manufacturer often associated with silence, would opt for an 80mm fan to cool the X900. However, as many previous reviews on Overclock3D have shown, 120mm fans can be just as loud as as their smaller counterparts when not controlled properly. The specifications for the fan used in the X900 can be seen below:

• Model: AD0812UB-A71GL
• Size (mm): 80x80x25
• Bearing: BALL
• Speed (RPM): 3900
• Airflow (CFM): 50.0
• Noise (dBA): 41.0

Cables & Connectors

Both the Molex, PCI-E and motherboard power cables are sleeved up to the very last connector in black mesh and finished off with zip ties covered in black heatshrink tubing. Strangely Seasonic have decided not to sleeve the SATA cables past the first connector, which makes the unit looks slightly untidy - and left me wondering why they didn't complete the job.

Seasonic X900 Cables Seasonic X900 Cables

However, it has to be said that the quality of the sleeving is exceptional and I was also pleasantly surprised to see that Seasonic have opted for 'Easy Grip' molex connectors - making the removal of the connectors from devices easier.

Seasonic X900 PCI-E Cables Seasonic X900 PCI-E Cables

As you'd expect from a high-wattage unit, the X900 comes with a total of four 6-Pin PCI-E connectors for supporting SLI, Quad-SLI and Crossfire configurations. Support for the very latest 8-Pin PCI-E graphics cards is also provided by means of two extension cables included in the accessories pack.

Seasonic X900 ATX Cable Seasonic X900 EPS-12v

The ATX connector on the X900 is native 24-pin. However, as you can see above, a small block of 4 connectors can be broken off to switch the connector to 20-pin. As many motherboards still make use of the P4-12v 4-Pin connector, Seasonic have chosen to include two separate cables for P4-12v (4-pin) and EPS12v (8-pin) standards.
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Most Recent Comments

26-09-2007, 08:01:00

"Seasonic have always been known for their high-end range of silent PSU's. Will their latest 900w beast - the X900 unit live up to their reputation and our expectations?"


26-09-2007, 08:25:32

Quality review as always mate, and what an excellent performer. I'll have the stability and efficiency over other blingy high-powered units any day. Keep up the good work Quote

26-09-2007, 08:25:34

Mr. Smith
Almost 85% efficiency is very impressive.

Shame about the noisy fan, had they placed 2 fans in the unit - one intake, one exhaust - then the fans would not have had to reach full throttle like a single one does...

Quality PSU.Quote

26-09-2007, 08:30:25

Agreed, but you look at the load required (776w) to get it to be audible. Many probably wouldn't even get it to break a sweat.Quote

26-09-2007, 08:36:13

Mr. Smith

I did overlook that rather important detail... Probably why pcp&p is silent - never breaks a sweat, not even benching!

This seems like another PSU for life Quote

26-09-2007, 08:53:21

Yeah it's a very good PSU for sure. As you've pointed out, its unlikely most people will ever hear this unit at full throttle, because it needs some serious load for that to happen.

Of course, if you was hell bent on making it total silent, you could always swap out the fan with a SilenX or something. Not that I'd advise anyone to fiddle inside a PSU Quote

27-09-2007, 03:44:58

Jeeze that is a PCP&C rip off if ever I saw one... the silnecer sprigns to mind when I look at that. Similar internal layout, same exhaust fan and positioning etc. But that is a good thing - more manufacturers like PCP&C mean more stable and quality PSU's. A single rail would have been nice but excellent PSU none the less - whopping efficiency!Quote

27-09-2007, 10:02:33

it looks quality tbh...

i'd stil have a pcp&c over it any day...but i bet its cheaper than the pcp&c equivilant....Quote

27-09-2007, 17:30:53

Nice review, looks like a great little PSU, and don't take little literally lolQuote

27-09-2007, 20:56:23

Good review mate, I like the good/mediocre/bad breakdown in the conclusions section.

I have to say I do like Seasonic PSUs. Quote

28-09-2007, 10:16:45

This looks quite good, I need a new PSU for SLIQuote

28-09-2007, 15:31:34

Originally Posted by name='cube'
Jeeze that is a PCP&C rip off if ever I saw one... the silnecer sprigns to mind when I look at that. Similar internal layout, same exhaust fan and positioning etc. But that is a good thing - more manufacturers like PCP&C mean more stable and quality PSU's. A single rail would have been nice but excellent PSU none the less - whopping efficiency!
Quote from Dave Hammock @

SeaSonic M12 SS-700HM 700W [Performs as a Single +12V Rail PSU.] [Modular]

Up to +12V@56A, Rated@40C, Efficiency up to 85%, 3yr warranty

Corsair HX 620W [Performs as a Single +12V Rail PSU.]

Up to +12V@50A, +5VSB@3A

I think most manufacturers design around multiple rails to stay withing the ATX specification.

BitTech in their review of the Seasonic X900, state the Corsair is actually a 750w psu thats "under-rated" to 620w to guarantee silence. They suggest Seasonic should take the same approach with the X900 i.e. class it as a truly silent/quiet 700w psu. I guess if true in this respect with regards to silence you could argue the pcpwr is more like a corsair a 620w? ...well maybe a bit noisyer Quote

28-09-2007, 15:44:45

appologies if sounding like a troll as this was not intended! did a lot of research before purchasing my Seasonic X900 from for £116.32. This is about the same price as the PCPower Silencer 750 quad.

I can tell you this I am running:

Opteron 175 OC from 2.2 to 2.8GHz

X1900XT Crossfire Master + X1900XTX in crossfire OC to 688/1584 core/mem

2x 10000rpm raptors

2x 500GB WD RE2

2x 320GB WD RE

2x 200GB Seagate


under load the psu is cool and the fan runs idle speeds!Quote

28-09-2007, 15:49:34

Ye that system will only put out about what...300-400w?Quote

28-09-2007, 16:10:17

Originally Posted by name='Kempez'
Ye that system will only put out about what...300-400w?
i was wondering about the output, but I guessed it to be around 400-500. i got the Seasonic to replaced my old PCPower 510 SLI turbo cool. I wasn't having much joy running crossfire. the cards were intermitantly not responding a little to frequently for my liking. this was occurring on a non-overclocked crossfire pc with a hard drive count of 6.Quote

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