Seasonic X900 SS-900HP 900w PSU



To put it simply, the Seasonic X900 is a wolf in sheep's clothing. Managing to keep the size of the X900 to not much bigger than your average ATX PSU, Seasonic have ensured that the X900 will work in a wide range of PC enclosures from spacious towers down to compact lanboxes.

This combined with the extremely impressive efficiency figures of almost 85% and minimal voltage fluctuation across each of the X900's rails shows Seasonic's dedication to not only manufacturing power supply's with excellent performance, but consideration for the environment and of course your energy bills too!

Currently priced at just under £130 over at Aqua-PC's and Scan, the X900 is at an amazingly good price point that can currently only be matched by lower wattage units from other manufacturers.

AquaPC's Recommended Retailer

The Good
• Very good voltage stability on all rails.
• Extremely high efficiency of almost 85% reported by our equipment.
• Dimensions not much larger than a standard ATX PSU.
• Very competitive pricing for a 900w unit.
• Silent up to and beyond 50% load.
• 4x PCI-E cables and support for the latest 8-Pin PCI-E standard.

The Mediocre
• 80mm fan gets a tad noisy at 100% load.

The Bad
• Nothing to report.

In recognition of these excellent qualities I need to congratulate Seasonic for managing to obtain Overclock3D's "Best In Class" award. This award signifies that the Seasonic X900 900w PSU is considered by Overclock3D to be the best all-round power supply in the 900w and above classification for the month of September, 2007.

Best In Class Award
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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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