Reviews - Seasonic X-400 Fanless 400W
Sample Provided by: (By OklahomaWolf on Mon, Sep-13-2010)

Page 1 - First Look

Greetings once again, good readers of mine. It's been a rather long time since I last got to test my mettle with a fanless power supply, but after several long months the wait is over. Ladies, gentlemen, aliens, llamas, today I give you the latest from Seasonic in the fanless X series 400 watt unit. This is exactly what you think it is, unless you thought for some inexplicable reason this was a toaster - a version of the original X-650 and X-750 units designed to run from nothing to full power without a fan.

You will recall that the more powerful X series units were designed to be semi-fanless from the get go. Seasonic was able to do this by designing an extremely efficient platform that made good use of open space inside the unit. Like its big brothers, this unit is also certified for 80 Plus Gold.

Our first stop on today's box tour is the back of the box, where there's a fair bit of marketing goodness.

  • Seasonic Patented DC Connector Panel with Integrated Voltage Regulation Module
    Seasonic patented full modular design minimizes voltage drops and impedance and maximizes efficiency and cooling and enhances overall performance and reliability.
    • Minimizes line resistance and voltage drops to maximize efficiency.
      -Hmm, I don't know about that one. A soldered down wire is always going to be slightly better at this than a connector. Still, this isn't what I'd consider a big deal when your average PSU modular connector is the same thing you see at the other end of the cable - a Mini Fit Jr style connector which is pretty reliable as connectors go.
    • Reduces overall component count to better space utilization for optimal air flow, heat dissipation and cooling.
    • Extensive use of SMD technology for overall quality and reliability improvement.
    • Simple and ingenious design for a "clean" layout to achieve unsurpassed quality and performance.
  • 80 PLUS® GOLD Certified
    80 PLUS® GOLD certification in combination with our corporate slogan "Green Innovation Powers Your Life", defines Sea Sonic's commitment to the design and production of the most eco-friendly power supplies on the market today with the X series as the market leader.
  • Fanless
    0 dBA
    -This is another one I have to take some issue with. This is a nearly impossible feat to accomplish. Yes, this unit is fanless. However, the reality is there will usually always be some noise emitted from the electronic components themselves. But, since I have no way to evaluate this claim, it will have to stand on its own today.
  • High Current Gold Plated Terminals
    Reduces current transmission resistance for increased efficiency.
    -Oh boy! Gold plated! I'm going to whip out my best CDs, hook this puppy up, and see if the sound quality is any better!
  • High Reliability 105°C Grade A Capacitors
    Built with top level Japan sourced components which translates to extended product life.
    -While this can have an effect on product life in comparison to some of the lesser quality capacitor brands out there, I'll remind you that there is more to a power supply's reliability than merely what capacitors are used. What matters more is how well engineered the unit is. I'm not worried - Seasonic hasn't disappointed me yet in this regard.
  • Conductive Polymer Aluminum Solid Electrolytic Capacitors
    Ensures operation stability at extreme conditions.
    -Actually, this may be the one time where I'll agree that polymer caps offer a substantial advantage over aluminum electrolytic capacitors. Fanless units like this get hot, and without a fan to cool things off, hot spots can develop that start pushing the limits of capacitors. Polymer caps tend to do a little better with heat in terms of retaining their electrical characteristics.
  • 5 Years Warranty
    Our commitment to superior quality.

This is the side of the box, at a size large enough for you to read. This will tell you how many connectors there are, what protection circuitry is present, what the power limits of this unit are, as well as a few other pertinent specifications.

Aha, more marketing. This is pretty much the same thing we saw on the back of the box, only in seven languages I can't read. It's all Greek to me. Wait... "Deutsch" means "Greek," doesn't it?

Upon opening the box, I was confronted with an IMPORTANT NOTICE. But before I show that to you, I must unpack.

There's that IMPORTANT NOTICE again. Along with a power supply with a sash around it, an owner's manual, a gigantic X series sticker, a bag of modular cables, a power cord, several zip ties, several velcro cable ties, some screws, and a Seasonic case sticker.

Here's a close-up of that IMPORTANT NOTICE. Take heed, folks - like most fanless units, this puppy will not be able to help you cool off your case. In fact, yours truly would strongly suggest that the presence of a fanless unit makes it all the more vital to insure your case has some decent airflow moving through it by other means. This includes setting up a positive or negative pressure situation whereby you can still get some air moving through the power supply. Fanless or not, you still need to provide for the cooling of this here power supply if you want it to stay working.

Here's a close-up of that massive X series sticker.

This is the owner's manual. It's a relatively complete affair which apparently covers the entire range of units in the series, from the unit I'm looking at today all the way up to the new 1200W model I've heard tell about.

Here she is, folks... Miss Fanless Power Supply 2010! The words on the sash in the above picture are pretty much self explanatory. Being fanless, this unit is convectively cooled so you need to have the heatsinks reaching for the sky if you can. Pull a gun on them and say "stick 'em up" if they get ornery.

Some of you may be running about in a panic wondering if your case's mounting holes will allow you to mount this unit properly. To you, I say fear not - Seasonic has thoughtfully provided extra mounting holes that allow this unit to be mounted properly in just about any case. Now, to get that sash off there so you can see this unit properly.

The color matte black is well represented again here today.

This unit, as you can see, has ventilation holes everywhere. Top, bottom, front, back, and both sides - all have room to breathe.

A shot from straight down into where the fan would normally be. I see lots of heatsinking, which is a necessity on a fanless unit like this.

A look at the back of the unit and the large gold colored heatsinks on the primary side. One certainly cannot fault the amount of real estate covered by grilles on this unit. It almost looks like a cage with some capacitors and stuff in it.

What did I tell ya? Grilles everywhere.

As was the case with the other X series units I've tested, the DC-DC topology of this unit leads to some serious power being available on the single 12V rail. In days of yore, you wouldn't have found a 400W unit able to hit 33 amperes at 12 volts. Not any honest units, anyway. This is because the VRM approach for the 3.3V and 5V rails all drawing power from one main 12V rail means extra complexity to the circuit design. Since extra complexity means extra cost, this is an approach that hasn't historically been used that often on smaller units like this. People will only pay so much for a four hundred watter, and this unit is not cheap for a unit this size. The only way to really make it worthwhile and cost effective to the manufacturer is to offer something most other 400W units don't.

Like fanlessness.

Seasonic X-400 Fanless

+3.3V +5V
-12V +5VSB
20A 20A 33A 0.5A 2.5A
Max Power 100W 396W 6W 12.5W

Here's the modular connector panel. This is basically the same kind of thing as the larger X series units, only with a fair few less connectors. Not that a 400W unit is going to power an SLI rig or anything power hungry, though. This unit likely has all the modular cables it will support.

Here are the modular cables. Nothing too surprising or amazing about these - they're all well sleeved. I just about yelled at the power cord for being in the shot too, but then remembered that technically it too is a modular cable. So, I decided it could stay.

Type of connector: Seasonic X-400
Modular Cables
ATX connector (590mm) 20+4 pin
4+4 pin EPS12V/ATX12V connector (650mm) 1
6+2 pin PCIe (600mm) 1
5.25" Drive (560mm+150mm+150mm) 3
5.25" Drive (360mm+150mm) 2
5.25" Drive to Dual 3.5" Drive Adapter (+150mm) 1
SATA (540mm+140mm+140mm) 3
SATA (350mm+150mm) 2
Unit Dimensions (L x W x H)
160mm x 150mm x 86mm

I have no serious complaints about the cable and connector count on this unit. It's good to see the varying length approach once again on the peripheral cables, which should make for somewhat easier cable management.

My first instinct was to take issue with it having only that one PCI-E connector, but then again this is a 400W unit. You're not going to want to run a 300W video card off this thing - it's just not big enough for that.


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