Seasonic Platinum 520 Fanless 520-Watt 80 PLUS Platinum Power Supply Review

Introduction, Specifications, Availability and Pricing

We really do hope that our readers are familiar with Seasonic by now. Over the last 35 years, they have become synonymous for high quality and efficient power supplies. Seasonic not only produces power supplies under their own name, but also acts as an OEM for a very large number of different manufacturers. Chances are that if you've had five or more power supplies throughout the years, one of them was built by Seasonic.

On top of all this, we've covered several of their units and they really are top notch. Our last review of a Seasonic unit was the Platinum 1000W and it was superb. It did leave us wanting more though and Seasonic has expanded their Platinum lineup with more units. Not only that, but their sub-600W units are available as fanless units.

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We have one such unit on the bench today and it is the 520W model. Keep reading as we go over the new Platinum Fanless 520W and see what it has to offer.

Specifications, Availability and Pricing

As you would expect from a lower wattage power supply, 12V power is delivered via a single 12V rail. In the case of the Platinum 520 Fanless, it is a 43A rail capable of 516W of power. Both the 3.3V and 5V rails are rated for 20A each with a combined maximum output of 100W. The 5VSB rail is rated for 2.5A or 12.5W. Maximum combined output for the power supply is 520W.

I'll be the first to admit that I was surprised when we weren't able to fill our feature summary full of green checks since this is a Seasonic unit. It is understandable though, since the power supply is fanless and it isn't intended to be in very hot environments. All protections are present including Over Temperature Protection. All cables for the Platinum 520 Fanless are both modular and fully sleeved. The power supply is 80 PLUS Platinum rated for efficiency and while it is not rated for 100% continuous output at 50C, it is rated for it at 40C.

Seasonic has an MSRP of $149.99 on the Platinum 520 Fanless power supply. A quick search will yield a much lower price of $134.56 from Provantage. This may seem like quite a bit for a 520W power supply, but let's not forget that it is fanless... and actually comes in cheaper than the competition by at least $10. Seasonic backs the Platinum 520 Fanless by a seven year warranty.

Packaging

Little information is available on the front of the package, but we do get a good glimpse of the unit and can see that plenty of passive ventilation is present.

The left half of the back goes over the efficiency of the unit and DC to DC regulation.

The other half gives us a shot inside the unit, claims super tight voltage regulation and silent operation.

One side is void of any information while the other provides us with some features and the I/O specifications of the power supply.

Both top and bottom are the same and feature no additional information.

Inside the Box

As you would expect from Seasonic, the Platinum 520 Fanless is packed very well.

Pulling the power supply out of the felt bag reveals a friendly reminder that this power supply cannot be installed however you want. The vent on top needs to stay facing up, regardless of the power supply being in the top or bottom of the case.

Extra ventilation is present on the bottom of the unit as well as the I/O specification label.

There is more passive ventilation on the side of the unit.

Swinging around to the other side we find a larger vent as well as the Platinum Fanless series logo.

On the back of the power supply you will find more venting as well as the AC input and on/off rocker switch.

The Platinum 520W Fanless is fully modular. All connections are clearly labeled. Yep, that is more venting in the front too. Every little bit helps.

A very large honeycomb mesh grill is in place of what would normally be the fan on the bottom of the power supply. Minimal obstruction here allows for excellent dissipation of heat passively.

All of the cables for the power supply are modular and either fully sleeved or of the flat ribbon type.

Included in the package are some Velcro cable ties, mounting screws, case badge, zip ties and AC power cord.

Also included with the power supply is a warranty card, user manual and important reminder not to do dumb stuff. That SFF chassis you've got that you plan running without fans and stuffing inside a closed cabinet? Yeah, this PSU doesn't belong in there.

Cabling Arrangement and A Look Inside

Cabling Arrangement

You simply couldn't ask for much more as far as connectors and cables go here. Short and long peripheral cables make this nice for keeping cable clutter down in smaller cases. Dual PCI-E cables mean that you can power up to a single high-end GPU as well. If anything, we would have liked to see an additional long SATA cable.

Rail distribution is as simple as it gets with a single 12V rail. There is no need to worry about load balancing here.

A Look Inside

As you would expect from a fanless power supply, the Platinum 520 Fanless has plenty of heat sinks on the inside of the unit. There are even some on the back of the front connector panel since it has voltage regulation built into it.

Something that I don't think that we've ever seen inside a power supply here at TweakTown is a Hitachi capacitor. Now we have.

Nippon Chemi-Con capacitors are present on the secondary side of the Seasonic Platinum 520 Fanless power supply.

Test Results and Final Thoughts

Test Results

Our load tests utilize a couple of FAST ATE active load testers and a variety of other equipment such as an oscilloscope, power conditioner, temperature probe and a power consumption meter. You can read more about our standard testing approach here.

The tests performed are based around six conceivable setups that are out there and progressively load down the PSU up to the power supply's limits or 1000W, whichever comes first. Since our test equipment's limits are higher than that of the Seasonic Platinum 520 Fanless 520W power supply, we can test it to the maximum.

The above tests represent typical loads that we have measured from various systems and are meant to give a rough idea of where your computer might fall in line with our tests. Please keep in mind that each system is different and actual loads can vary greatly even with similar hardware.

Let's start by taking a look at the voltages to see how well this unit did during testing. Starting with the 12V rail, we see 1% regulation from start to finish with a total drop of .05V. The 5V rail managed to stay within 1% of specification with a total drop of .02V from start to finish. Moving towards the 3.3V rail, we see that regulation was within 1% of specification with a total voltage drop of .04V.

DC Output quality for the Power Force 850W was excellent and well within specification. During Test 1, we saw 18mV of noise on our scope. When we increased the loads in Test 2, the ripple climbed to 26mV at a little over half load. During Test 3 under a load of 520W, the oscilloscope showed a maximum of 35mv on noise on the 12V rail.

Seasonic Platinum 520 Fanless is rated for 80 PLUS Platinum efficiency. This means that the power supply must perform at 90%/92%/89% efficiency at 20%/50%/100% loads respectively. As you can see, the Platinum 520 Fanless passed on our bench, and wasn't close to failing at any point.

Final Thoughts

Once again we have another Seasonic unit that is nearly flawless on our test bench. Looking at the power supply from a performance standpoint, it is perfect. Voltage regulation is kept at an impeccable 1% across the board while DC output quality is amazing as well. The Platinum 520 Fanless also performs with Platinum rated efficiency as advertised.

None of this is an industry first. We've seen 1% regulation with a handful of units in the past and we've also seen extremely low ripple on the 12V rail, too. Platinum efficiency isn't anything special either, as we've seen it from just about everyone in both actively and passively cooled variants. What is special and an industry first is that it is all wrapped up in a single package all while being cheaper than most other fanless power supplies of similar wattage. It is very clear that the Platinum 520 Fanless represents the pinnacle of everything that Seasonic has been able to achieve in over 30 years of R&D.

If you're in the market for a fanless unit, you'll be doing yourself a disservice by not strongly considering the Seasonic Platinum 520 Fanless 520W power supply above the competition.