Introduction

Are you tired of reading reviews of high output power supply units? It's true that 99% of personal computers out there do not require something capable of outputting more than 500-550 Watts, and even that may be overkill for quite a few people. Even though high output units are often the most interesting in terms of the technologies being used and their potential audience is very demanding, we understand that the bulk of any company's revenue comes from the low-budget and mainstream units.

Today we have something different for you, as we are going to look at the Silverstone Nightjar 520W power supply, a PSU with a moderate power output but a very distinct feature: it's completely fanless. Fanless PSUs are not a new idea, with models appearing as early as the 90's, but the early models still had to rely on massive heatsinks, usually in conjunction with heatpipes -- sometimes even using their entire body as a heatsink as well. This obviously gave them a fair share of disadvantages and increased their cost significantly. The Silverstone Nightjar 520W retails for about $139.99 including shipping (after rebate), a steep price for a 520W unit, even for an 80Plus Platinum certified model. The price is obviously due in large part to its fanless nature. Does it perform well enough to justify such a price? We will find out in this review.

Packaging and bundle

We received the NightJar NJ520 inside a standard cardboard box with a somewhat understated and straightforward aesthetic design, with the unit's major features printed on the front side of the box in English and on the rear side of the box in nine other languages. Inside the box, the PSU is protected by polyethylene foam pieces.

Alongside with the unit, the user will also receive a black and white manual, an AC power cable, a few cable straps, and five high quality Velcro cable ties.

The NJ520 is a fully modular power supply. Its cables come supplied inside a dual nylon pouch and they are all black. Silverstone went with ribbon-like, "flat" cables, with the exception of the 24-pin ATX cable, which is comprised of only black wires covered by black sleeving.

External Appearance

In terms of size, the Nightjar NJ520 appears just like any other modular ATX PSU. Its silver chassis is 160mm deep, making it suitable for all ATX compliant cases. It is however noticeable that the PSU lacks a fan. The sides of the Nightjar NJ520 are perforated and, as the warning label indicates, the top side of the chassis has to be facing upwards when it is installed in a case, as the cooling scheme relies on convection via passive airflow. This will not be a problem for most modern tower cases, as they have a PSU compartment at or near their bottom; however, it will most certainly be an issue with tower cases that have the PSU compartment above the motherboard tray, or with most desktop/HTPC cases.

The front side of the chassis has even more openings for passive airflow, as well as the modular cable connectors. The connectors are black and there is a legend printed on the chassis, although they are keyed and you cannot install a cable into the wrong connector. The rear side is similar to that of any other ATX PSU, with an AC cable plug, a small switch and a metallic sticker with the series name beneath it.

Internal Design

After looking inside the Nightjar NJ520, we quickly identified that it is a Seasonic design, the one Seasonic is using for their own Platinum 520W Fanless model. There is a very strong filtering stage, partially shielded, consisting of six Y capacitors, three X capacitors and three filtering inductors. There is also a relay, which cuts off the AC supply to the unit entirely once it is turned off, to minimize losses while the system is powered off.

Despite the low output of the unit, there are two parallel rectifying bridges mounted on their own heatsink. The active APFC components, two transistors and a diode, are on the large heatsink near the edge of the PCB. The primary inversion stage consists of four switching transistors, forming a full bridge topology. The 12V conversion stage components are cooled by the U-type heatsink seen on the secondary side of the transformer. Only a 12V line is generated; the minor 3.3V and 5V lines are converted from it via DC-to-DC circuits that are on the connector's board.

A Hitachi 330μF / 420V capacitor is present for the APFC circuit. All of the secondary capacitors, electrolytic and polymer alike, are supplied by Nippon Chemi-Con. The quality of the soldering is very good, although not the best that we have seen and with a few hand-made joints. Glue is used to strengthen the unit mechanically, improving its reliability and reducing the chance of high frequency vibrations (coil whine noise).  

Cold Test Results

For the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M  40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs - 2014 Pipeline post.

Since this power supply is fanless, we are going to have two fewer graphs in this review. The first one is the noise chart, as this product has no moving parts and thus does not generate any noise, and the second one is the air temperature chart, as this method cannot be accurately applied if there is no forced airflow.

The electrical performance of the Nightjar NJ520 is excellent, which was to be expected from a Seasonic design. At room temperature, the Nightjar NJ520 easily meets the 80Plus Platinum certification and displays an average energy conversion efficiency within the nominal load range (20% to 100%) of 93.0%. Loads lower than 50 Watts however have a significant impact on the efficiency, which drops below 80%. This does not affect the 80Plus certification, which takes into account only the 20% to 100% nominal capacity range.

Even though it is a very efficient model, the Nightjar NJ520 remains surprisingly cool for a passive power supply, with the temperature of the primary and secondary heatsinks reaching up to 56.4 °C and 57.0 °C respectively. Although these figures are relatively high for a 520 Watt model in room temperature, the Nightjar has no forced cooling and therefore it is perfectly natural for it to be warmer than typical units.

Hot Test Results

From the tables below, it can be seen that the output power quality of the Silverstone Nightjar NJ520 is exceptional. The maximum voltage ripple that our instrumentation recorded was 34 mV under maximum load. Even with the unit heavily cross-loaded, the ripple on the 12V line only went up to 46 mV, which is much lower than the 120 mV design limit. Voltage regulation is less than 1% for the 12V line and just over 1.2% for the minor lines, performance figures that are excellent and comparable only to those of top-tier products.

Although this unit is rated for operation with an ambient temperature of up to 40 °C, it performed just fine even with an ambient temperature of 50 °C. The energy conversion efficiency is reduced by about 0.4%, a fantastic result for increasing ambient temperature by 25 °C.

As the Nightjar NJ520 has no fan, the increase in ambient temperature essentially increases the operating temperature of the unit almost proportionally. The temperature of the primary and secondary side heatsinks is now reaching up to 81.9 °C and 84.1 °C respectively, figures that would make us feel uncomfortable but are not high enough to trigger a thermal shutdown by the protective circuit of the unit. The Nightjar NJ520 will simply shut down if overheated, as it has no active cooling and thus it cannot take any action to change its thermal performance. Obviously it's not really intended to be run in such extreme conditions, so plan accordingly.

Conclusion

Even though fanless computer PSUs are not a new concept, SilverStone's (or to be exact, Seasonic's) latest design is a refreshing approach. By greatly improving the energy conversion efficiency, there is no longer any need for bulky and expensive cooling solutions or even for exotic designs. The Nightjar NJ520 is very similar to any typical ATX-compliant PSU, with the exception of the "missing" cooling fan. Certain components and the heatsinks are oversized for a 520 Watt model, plus there are more ventilation openings, but that's where the major differences with a typical PSU end. It is very likely that the same exact platform will be found retrofitted with an active cooling system and minor other tweaks, selling as a 700-850 Watt unit, as the design can easily handle such output with the addition of active cooling.

When it comes to performance however, the Nightjar NJ520 is astounding. Seasonic's designs have always been well above average, but the electrical performance Nightjar NJ520 is nothing short of fantastic. This may be due to the oversized circuitry and components, which are usually found in units of higher output, allowing the Nightjar NJ520 to combine exceptional energy conversion efficiency and power output quality. The result is very high efficiency, which is not easily affected by temperature, and very low voltage ripple, from a power supply that generates zero noise as well.

Aside from its excellent performance, quality is another very strong characteristic of the Nightjar NJ520. Silverstone's choice of components has been excellent, as we failed to find even a single average-quality part inside the Nightjar NJ520. All of the capacitors, electrolytic and polymer alike come from highly reputable Japanese manufacturers, and the quality of the assembly and the soldering job are excellent as well, making the Nightjar NJ520 a truly well-made product. Warranty information regarding the Nightjar NJ520 is a bit hazy, as the length of the warranty is not specified on the box or even in the manufacturer's website; however, Silverstone covers the vast majority of their products with a three year limited warranty, and we believe that it includes the NJ520 even though the model is not specifically listed at the time of this review.

The high quality and oversized design however also are the source of this unit's major weakness. Since the Nightjar NJ520 is significantly oversized and essentially comprised of parts normally meant for more powerful units, it also is equally overpriced for a 520 Watt power supply. With a retail price of $139.99 including shipping (after rebate), the price tag of the fanless Nightjar NJ520 is almost equal to that of 750 Watt 80 Plus Platinum PSUs (which of course include a fan for active cooling). Overall, the Nightjar NJ520 is a very high quality fanless modular PSU with excellent electrical performance; whether the fanless design is worthy of such a premium price however heavily depends on the budget and priorities of the user. If your priority is noiseless operation combined with great overall performance and quality and you are willing to pay the rather steep price to get what you want, the Nightjar NJ520 will not be a disappointment.