Seasonic X900 SS-900HP 900w PSU

Introduction & Specifications


Over the past 30 years Seasonic have gained a reputation for manufacturing some of the most silent and stable power supplies in the market. With models such as the S12 as part of their portfolio, Seasonic will always be one of the first names mentioned to those seeking silence without compromising performance.

Back in November 06, we were given the chance to test their first ever modular PSU:- the M12. With unique modular cables and decent performance the M12 design was head-hunted by memory giants Corsair. After some minor alterations to the cooling layout of the M12, Corsair released the unit as their now extremely popular HX series.

With more and more high-powered units entering the market from a whole range of manufacturers it's hard to stay with the same product for too long, and for this reason Seasonic have released a new high-end, performance orientated unit named the X900. The X900 power supply is (not surprisingly) rated at 900w, has quad PCI-E connectors and most interestingly of all - an 80mm fan. Today I'll be putting this unit though its paces, comparing its performance to other similar units and finding out if Seasonic have managed to keep their finger on the pulse since the release of their last PSU almost a year ago.

What Seasonic Say:

Since the incorporation of Sea Sonic Electronics Co., Ltd. in 1975, we have maintained our focus on research and development and the production of quality power conversion products.

For the past decades, supported by cutting edge technology based upon a strong research and development team, Sea Sonic Electronics has provided timely and professional solutions to meet many of the IT industry's requirements.

For the future, we will continue our philosophy of dedication; innovation, professionalism and 4G's (Great Technology, Great Quality, Great Service & Great Price) in order to maintain our goal of continued long-term business partnerships and create "win-win" situations for our customers.


The following information has been taken directly from Seasonic's recent press release and Nanopoint's (Seasonic's UK Distributor) website:

Seasonic X900 Power Supply – Ultimate Power & Performance

The Seasonic X900 is designed and built for power, performance, stability and reliability as demanded by power users, gamers and over-clockers. The X900 is a true 900W output power unit with a peak output of over 1,000 watts.

Seasonic X900 is equipped with multiple +12V rails to support high-end graphic cards’ need with a total power output of 72 amps. A Double Forward Converter circuit design achieves a 99% Active Power Factor Correction and an industry-leading efficiency rating of up to 88%. Additionally, the power supply utilizes a Dual Magnetic Amplifier circuit to maintain a class-leading 3% line regulation tolerance on all +12V output rails to meet the demands of high-end graphics cards, CPU’s and peripherals for accurate and stable power output.


• Super high efficiency for energy savings, up to 88% efficiency
• 3% line regulation for +12v rails for maximum stability, security and performance.
• Multiple 12V outputs with enhanced +12V current capability to broaden utilization capabilities.
• High reliability aluminium electrolytic capacitors for increased product life and reliability.
• Active power factor correction [99% PF] for reduced line noise and power distortion.
• Advanced dual forward converter circuit design for added reliability and efficiency.
• Smart and silent fan control [S2FC], one of the best-performance noise controllers available on the market.
• 8cm double ball bearing fan for increased lifetime.
• 4x PCI-Express connectors to support high-end graphic cards. With 6p to 8p PCI-E adapters x2
• All in one DC cabling to support PC, IPC, workstations, servers and dual CPU systems.
• Patented easy swap peripheral connectors for easy plug and unplug connection.
• Total protection with Over Voltage, Over Power and Short Circuit protection.
• Fixed 220V AC input.
• >100,000 hours MTBF, excluding fan.
• RoHS compliant.
• PFC harmonics compliant, EN61000-3-2: 2000
• EMI/ EMC: CE, C-tick & safety approvals: CB, TUV & Semko

As we can see from the specifications above, the X900 provides support for the latest 8-Pin PCI-E powered graphics cards along with multiple +12v rails that Seasonic tout as offering enhanced stability, security and performance.

In addition to this, the X900 is rated at a whopping 88% efficiency. If these figures are indeed confirmed in our testing, this will make the X900 the most efficient PSU we've ever tested!

Seasonic X900 Specs

The X900 has a total of four +12v rails, each rated at 18 amps. This may not seem very impressive considering lower wattage PSU's such as the Tagan 2-Force II 700w quote output of 20 amps across four rails, but what we need to keep in mind is the total combined output of the unit. In the case of the X900 the total combined output is a whopping 72 amps, whereas units such as the Tagan may only be able to produce around 50 amps.
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Most Recent Comments

26-09-2007, 12:25:32

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, 12:25:34

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, 12:30:25

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, 12:36:13

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, 12:53:21

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

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