Kilowatt of Platinum: Seasonic SS-1000XP Active PFC F3 Power Supply Unit Review

We were among the first to get our hands on the newest 1000 W Seasonic PSU – the first model certified as 80 PLUS Platinum. Let’s see what this award-winning solution is capable of.

by Dmitry Vasiliev
11/21/2011 | 09:28 AM

The majority of power supply units that sport 80+ certification only comply with the basic or Bronze requirements of that standard. The Silver certificate is downright unpopular. The number of 80+Silver products on the official list is only half of the 80+Gold ones and about one fifth of the 80+Bronze ones.


There is, however, one more category of 80+ products which are even rarer than the Silver-certified PSUs. They are referred to as Platinum. We, at X-bit labs, have never had any of them for us to test although they already number over half a hundred. This is not a big number, though, if you consider that the Platinum requirements were introduced over two years ago, in October 2009.

So, today I’m pleased to review one of the most expected Platinum-certified PSUs of this season: Seasonic SS-1000XP Active PFC F3. It is the more powerful model of the two Platinum-certified PSUs that Seasonic offers (its junior cousin has a wattage rating of 860 watts and provides only four 6+2-pin graphics card connectors; its +12V load capacity is lower by 12 amperes, too).

Testing Methodology

Click the following link for a description of our testing methodology and equipment and a brief explanation of what the specified and tested parameters of power supplies mean: X-bit Labs Presents: Power Supply Units Testing Methodology. If you feel overwhelmed with the numbers and terms this review abounds in, refer to the Methodology.

You can also go to our Cases/PSU section to check out reviews of all other PSU models we have tested in our labs.

We will mark the actual power consumption of three system configurations (discussed in our article PC Power Consumption: How Many Watts Do We Need?) in the cross-load diagrams. This will help you see if the tested PSU can meet the requirements of a real-life PC.

Closer Look at Seasonic SS-1000XP Active PFC F3

The most technologically advanced product in Seasonic’s line-up deserves special packaging.

The PSU is shipped in a bulky cardboard box with a shimmering holographic 80+Platinum logo. The shape and, in fact, the contents of the box are familiar to us after our tests of the Seasonic X Gold series.

Although it is still just a cardboard box rather than something completely original, it is certainly eye-catching. Unfortunately, it lacks a handle.

The PSU is wrapped up in protective material. The box also contains a pouch with a mains cord and power cables, a user manual and a pack with various small things.

The PSU is snugly packed into a black velvety pouch with manufacturer’s logo.

The cable pouch has two separate compartments that can be attached to each other with Velcro fasteners (there is a mains cord in between them in the photo).

The accessories include three cable straps with Seasonic logo, a few single-use plastic straps, a “Power by Seasonic” sticker, and a set of screws for fastening the PSU inside your system case.

Exterior Design

The SS-1000XP Active PFC F3 is painted dark and gray and features all-modular design. It has not a single fixed cable. It resembles Seasonic’s X Gold series but is larger: 190 as opposed to 160 millimeters.

The fan is covered with a gray honeycomb-mesh grid (this grid is just punched out in the case of X Gold series PSUs). There is a manufacturer’s logo on the fan grid.

The back panel is a vent grid, too. Its openings are the same size and shape as those of the fan grid. There are also a vertical mains connector and a large I/O switch at the back.

The rest of the panels are black, lacking any slits or openings except for the connectors for detachable power cables.

Just as is the case with the X Gold series, it’s not simple to dismantle this PSU. First you have to take off the cover with cooling fan, then remove the bottom of the case with the connectors panel, and finally take off the U-shaped piece of the side and back panels.

Circuit Design

The SS-1000XP Active PFC F3 looks different from many regular PSUs but shares many common traits with Seasonic’s X Gold series.

There is an unusually high number of solid-state capacitors, just like in the X Gold series.

The component density is high, notwithstanding four daughter cards (two large and two tiny ones), the large size of the main PCB, and the fact that the latter has quite a number of components on its reverse side.

The small size of the heatsink doesn’t come as a surprise because there is no need for better cooling if the PSU is over 90% efficient.

Again, the reverse side of the main PCB is where quite a large number of small components are installed. The quality of soldering is perfect everywhere in this PSU.

For the reverse-side components not to touch the bottom of the case, the PCB is insulated with a sheet of transparent plastic. The large cutout in the top left of the photograph is covered with a soft pad on the bottom panel that ensures insulation as well as cooling.

The PSU has high-quality KZE and KZH series capacitors from United Chemi-Con at the output.

Of course, a PSU of this class can’t do without dedicated voltage regulation: the +5V and +3.3V voltage regulators reside on the daughter card together with connectors for detachable power cables.

Chokes and solid-state capacitors can be seen on the connectors side of the card.

Resistors and controllers are on the other side.

The main PCB only yields +12V.

Cables and Connectors

The SS-1000XP Active PFC F3 has the following connectors:

This selection of connectors is going to be sufficient for any computer configuration while the short PATA and SATA cables will help avoid clutter if you don’t need long ones. The rest of the cables are long enough to comfortably connect everything even in a huge system case.

I can only find fault with the graphics card power cables which are used in pairs. One cable will be redundant if your graphics card has only one power connector. On the other hand, the very specifications of this PSU imply that it is designed for multi-GPU configurations with up to three top-end graphics cards, each of which has two power connectors.


The SS-1000XP Active PFC F3 is up to today’s requirements in its specs. Its +12V rail is not split up into multiple “virtual” output lines and can yield up to 996 watts, which is close to the PSU’s full output power of 1000 watts.

The load capacity of its +5V and +3.3V rails is high enough for any modern PC configuration as well.

UPS Compatibility

Working together with my APC SmartUPS SC 620, the PSU was stable at loads up to 398 watts when powered by the mains. The UPS could switch to its batteries at a PSU load of 370 watts. If the load was 380 watts, the PSU would shut down quietly, the UPS not even emitting its customary overload scream.

That’s excellent behavior. The SS-1000XP Active PFC F3 is compatible with my UPS at higher loads than average in my tests. And if the load gets too high, it won’t scare you with overload warnings.

Output Voltage Stability

Besides other things, the user manual says that this PSU is going to keep the output voltage within a 2% deflection from their default levels. And it does:

Every voltage is always within the promised 2% deflection. The +5V voltage is even within 1% except at extremely low loads.

The PSU could start up at zero load, too.

Output Voltage Ripple

The high-frequency voltage ripple is higher than with the X Gold series but far below the requirements of the industry standard.

The same goes for the low-frequency ripple at the double mains frequency.

Temperature and Noise

Large fans have become conventional in PSUs, but the SS-1000XP Active PFC F3 can do with a modest 120mm fan thanks to its high efficiency. There should be no problems in terms of cooling and noisiness if the fan regulation algorithm is right (the high-efficiency FSP Aurum series is a bad example of such an algorithm).

The PSU is cooled by a Sanyo Denki fan (San Ace 120, 9S1212F404) that is also employed in other products from Seasonic and Corsair. Seasonic claims that this model boasts a number of exclusive advantages: triple balancing of the copper axis, specially shaped blades that ensure high efficiency at minimum noise, long-lasting design with ball bearings. As a matter of fact, in our earlier reviews we noticed Sanyo Denki fans to have been individually balanced, which contributes to their low noise and long service life.

This fan is blameless, too. However, its honeycomb-mesh grid would produce some unwanted aerodynamic sounds when the speed of the fan was as high as 1000 RPM. On the other hand, this means very high loads at which there will probably be much more prominent sources of noise in the computer system.

The PSU’s fan can work in two modes: Normal (selected by default) and Hybrid.

You can change the mode by means of a switch near the connectors (when you install the PSU into a system case, that switch will be inside the chassis).

The default Normal mode means a standard regulation algorithm with the fan rotating at a low speed until a certain load/temperature. After that threshold, its speed begins to increase in a linear manner.

The low-load speed of the fan is about 650 RPM. It is only at a load of 700 watts that the fan accelerates and it does so proactively, reducing the temperature rather than just keeping it at the same level.

The Hybrid mode is going to be demanded by users who don’t often run heavy applications but value silence. The fan does not work at all when the load and temperature are low. As the load grows higher, the fan starts up at a very low speed (below 500 RPM) and then accelerates some more.

According to its specs, the PSU is cooled passively until a temperature of 25°C and loads of 30%, but in my test the fan would start up intermittently only at loads above 350 watts. The fan was rotating constantly at loads of 400 watts and higher. The ambient temperature was 23°C and the internal temperature of the PSU was surely higher than the specified 25°C for passive mode: the difference between the incoming and outgoing air was as large as 15°C.

The fan accelerates in a linear way at high loads and, just like in the Normal mode, the temperature goes down rather than stays at the same level.

This ensures better thermal conditions for PSU components, but the PSU might have been even quieter at high loads if its fan wasn’t so aggressive. Well, even with this regulation algorithm the fan is only 1000 RPM fast at a load of 800 watts. Its noise only becomes audible at loads of 900 watts and higher.

So, the two modes are roughly equal when it comes to high loads, but the Hybrid mode is quieter at low and medium loads (the fan doesn’t work at all at loads up to 350 watts and its speed is lower than in the Normal mode at loads up to 600 watts). On the other hand, the fan is very quiet at the speed of 650 RPM that it has at low loads in the Normal mode, so both modes are very comfortable.

Efficiency and Power Factor

The power factor is 98 to 99% through most of the load range, just as you can expect from active PFC.

As for the efficiency factor, I want to give you some clarifications as to the 80+Platinum requirements for 115V and 230V power mains.

On one hand, the PSU exceeds the 80+Platinum specs for 115V mains (90%, 92% and 89% efficiency at loads of 20%, 50% and 100%) but on the other hand, it falls short of the 80+Platinum requirements for 230V mains by about 1% in my test which was carried out in a 220V power grid (the PSU notched 94%, by the way, but only at 390 watts rather than at 50% load).

However, the 80+ standard only certifies PSUs for redundant, data center applications when it comes to 230V mains. Such PSUs are very different from ordinary PSUs for desktop PCs and workstations which are only 80+ certified for 115V mains.

A PSU should get somewhat more efficient after switching from 115V to 230V mains because of the reduced current strength. The Seasonic SS-1000XP Active PFC F3 gives us a good example as it is about 1% more efficient than the 80+Platinum requirements for 115V mains in this test.

Thus, it is a true 80+Platinum product even though its efficiency may seem to fall short of the 80+Platinum requirements for 230V mains (which are not applicable to it, as I’ve explained above).

+5V Standby Source

The standby voltage is very stable.


The Seasonic SS-1000XP Active PFC F3 is a real engineering masterpiece with its all-modular design, quiet operation up to very high loads, very high efficiency, stable voltages, low voltage ripple, good compatibility with UPSes and 7-year warranty. The only “problem” I can think of is that its box lacks a handle. Moreover, it may be pretty expensive, which is, actually justified by all means.

The only things I’d love to see improved are the cables: I wish it had flexible flat cables (like the FSP Aurum or Enhance EPS-1280GB4 units) and less aggressive behavior of the fan under high loads (I would rather have the fan keep the temperature at the same level instead of lowering it). On the other hand, I have to admit that the PSU’s current cables and acoustic performance are close to perfect already.

In fact, the Seasonic SS-1000XP Active PFC F3 seems to be the best PSU we’ve ever tested in our labs. We’ve seen quiet, high-wattage or user-friendly PSUs but none of them could offer all of these in a single package! Therefore, we are proud to award this product our Editor’s Choice title: