Introduction

SilverStone has released a completely fanless 400 W power supply, thus producing absolutely no noise, using a high-end design. Can it survive our tests? Let’s see.

The reviewed power supply is manufactured by FSP. Keep in mind that other SilverStone power supplies models can be manufactured by Seventeam, Enhance and Impervio.

Because it doesn’t have a fan, its top panel is actually a huge heatsink, as you can see in Figure 1.

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Figure 1: SilverStone Nightjar 400 W power supply.

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Figure 2: SilverStone Nightjar 400 W power supply.

Nightjar 400 W is 6 19/64” (160 mm) deep, featuring active PFC, of course.

All cables use nylon sleevings, but they don’t come from inside the power supply, as you can see in Figure 2. The included cables are:

• Main motherboard cable with a 20/24-pin connector.
• One cable with two ATX12V connectors that together form an EPS12V connector.
• One cable with two six/eight-pin auxiliary power connector for video cards.
• Two SATA power cable with three SATA power connectors each.
• Two peripheral power cables with three standard peripheral power plugs and one floppy disk drive power connector each.

The number of cables is more than perfect for a 400 W unit: it comes with two video card power connectors, while most 400 W units will come with only one.

All cables have 21 ¼” (54 cm) between the power supply housing and the first connector on the cable. On the video card power cable there is 5 ¾” (14.5 cm) between connectors, on the SATA power cables there is 5 7/8” (15 cm) between connectors and on the peripheral power cable there is 9 5/8” (24.5 cm) between the first and the second connector but 5 7/8” (15 cm) between the second and the third connector. All wires are 18 AWG, which is the correct gauge to be used.

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Figure 3: Cables.

Now let’s take an in-depth look inside this power supply.

A Look Inside The Nightjar 400 W

We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.

This page will be an overview, while in the following pages we will discuss the quality and ratings of the components used in detail. Pay attention to the top panel that is a big passive heatsink.

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Figure 4: Overall look.

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Figure 5: Top panel/main heatsink.

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Figure 6: Top panel/main heatsink.

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Figure 7: Overall look.

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Figure 8: Overall look.

Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil.

This power supply has all required components, plus two extra Y capacitors, one extra X capacitor and one X capacitor after the rectification bridge.

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Figure 9: Transient filtering stage (part 1).

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Figure 10: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion of the components used in the SilverStone Nightjar 400 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of SilverStone Nightjar 400 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one TS15P06G rectifying bridge in its primary, which can deliver up to 15 A at 100º C. At 115 V this unit would be able to pull up to 1,725 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning this component. Talk about overspecification! Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

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Figure 11: Rectifying bridge.

On the active PFC circuit two SPW20N60C3 power MOSFET transistors are used, each one capable of delivering up to 20.7 A at 25º C or 13.1 A at 100º C in continuous mode (note the difference temperature makes) or 62.1 A in pulse mode at 25º C, presenting a resistance of 190 mΩ when turned on, a characteristic called RDS(on) – the lower this number the higher efficiency is.

The electrolytic capacitor in charge of filtering the output from the active PFC circuit is Japanese from Chemi-Con and labeled at 105º C. This is terrific, especially because being a fanless power supply we would expect this unit to achieve a higher internal temperature.

The active PFC coil is attached to the primary heatsink, which is quite interesting.

In the switching section, two STP20NM50FP power MOSFET transistors, each one capable of delivering up to 20 A at 25º C or 12.6 A at 100º C in continuous mode (note the difference temperature makes) or 80 A in pulse mode at 25º C, presenting a maximum RDS(on) of 250 mΩ.

The switching transistors are connected using a design called “LLC resonant,” also known as a series parallel resonant converter, being controlled by an L6598 integrated circuit. The coil required by this design is also attached to the primary heatsink. So far we’ve seen only a couple of other power supplies using this kind of design, like Seasonic X-Series 650 W and Thermaltake Toughpower 800 W.

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Figure 12: Active PFC transistor and the two switching transistors. Note the resonant coil.

The active PFC circuit is controlled by a separated integrated circuit, an L4981A.

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Figure 13: Active PFC controller (left) and resonant controller (right).

Now let’s take a look at the secondary of this power supply.

Secondary Analysis

This power supply uses a DC-DC design on its secondary, meaning that it is basically a +12 V power supply with the +5 V and +3.3 V outputs being produced from the main +12 V output by two smaller power supplies. This design is used by several other power supplies and is proving to be a winner for building high-efficiency models.

The main +12 V output is produced by four STPS6045CW Schottky rectifiers , each one capable of handling up to 60 A (30 A per internal diode at 150º C, maximum voltage drop of 0.63 V). This means that the main +12 V output can, in theory, handle up to 171 A. Of course it is used by all outputs, but if all this theoretical current was delivered only to the +12 V output, this would give us 2,057 W. Is this power supply overspec’ed or what?

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Figure 14: +12 V rectifiers.

The +5 V and +3.3 V outputs are generated by four NTB125N2R Power MOSFET transistors (two for each output), each one capable of handling up to 125 A at 25º C with an RDS(on) of only 3.7 mΩ, which is very low (excellent). Once again, these outputs are amazingly overspec’ed. Each pair of transistors is controlled by an L6730 controller.

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Figure 15: +5VSB rectifier and transistors from the +5 V and +3.3 V power supplies.

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Figure 16: DC-DC controllers.

The secondary is monitored by a PS223 monitoring integrated circuit, which is in charge of the power supply protections, like OCP (over current protection), OVP (over voltage protection), UVP (under voltage protection) and OTP (over temperature protection, not implemented on this power supply).

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Figure 17: Monitoring integrated circuit.

Electrolytic capacitors from the secondary are from Teapo.

Power Distribution

In Figure 18, you can see the power supply label containing all the power specs.

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Figure 18: Power supply label.

This power supply uses a single-rail design, so there is not much to talk about here.

Now let’s see if this power supply can really deliver 400 W.

Load Tests

We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.

First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.

If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at 5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.

The +12V1 and +12V2 inputs listed below are the two +12 V independent inputs from our load tester. During this test both were connected to the single +12 V rail from this power supply.

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12V1	2.5 A (30 W)	5.5 A (66 W)	8 A (96 W)	10.5 A (126 W)	14 A (168 W)
+12V2	2.5 A (30 W)	5.5 A (66 W)	8 A (96 W)	10.5 A (126 W)	13 A (156 W)
+5V	1 A (5 W)	2 A (10 W)	4 A (20 W)	6 A (30 W)	8 A (40 W)
+3.3 V	1 A (3.3 W)	2 A (6.6 W)	4 A (13.2 W)	6 A (19.8 W)	8 A (26.4 W)
+5VSB	1 A (5 W)	1 A (5 W)	1.5 A (7.5 W)	2 A (10 W)	2 A (10 W)
-12 V	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)
Total	78.6 W	158.5 W	236.7 W	314.6 W	401.2 W
% Max Load	19.7%	39.6%	59.2%	78.7%	100.3%
Room Temp.	44.5º C	44.4º C	44.0º C	44.2º C	45.3º C
PSU Temp.	51.7º C	52.0º C	52.2º C	52.8º C	53.6º C
Voltage Stability	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	92.7 W	181.8 W	272.3 W	364.5 W	470.8 W
Efficiency	84.8%	87.2%	86.9%	86.3%	85.2%
AC Voltage	114.4 V	113.0 V	112.6 V	111.9 V	110.6
Power Factor	0.963	0.986	0.991	0.993	0.995
Final Result	Pass	Pass	Pass	Pass	Pass

SilverStone Nightjar 400 W is nothing close to an entry-level unit. It achieved an outstanding efficiency for a 400 W unit, between 85% and 87%, as you can see on the above table.

Voltage regulation was another highlight from Nightjar 400 W, with all positive outputs closer to their nominal voltages than required (3% vs. 5%), except the -12 V output, which usually doesn’t like to be so close to its nominal voltage (this output was inside its maximum limits).

Ripple and noise levels were always very low. Below you can see the results for test number five. The maximums allowed are 120 mV for +12 V and 50 mV for +5 V and +3.3 V. All values are peak-to-peak.

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Figure 19: +12V1 input with the power supply delivering 401.2 W (56.4 mV).

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Figure 20: +12V2 input with the power supply delivering 401.2 W (56.6 mV).

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Figure 21: +5 V rail with the power supply delivering 401.2 W (29.2 mV).

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Figure 22: +3.3 V rail with the power supply delivering 401.2 W (19.8 mV).

Now let’s see if we could pull more than 400 W from this unit.

Overload Tests

Before overloading power supplies we always test first if the over current protection (OCP) circuit is active and at what level it is configured.

In order to do that we put +5 V and +3.3 V outputs to pull only 1 A and increased current on the power supply +12 V rail until it shut down. This happened when we tried to pull more than 34 A from this rail.

Then starting from test five we increased currents to the maximum we could with the power supply still running inside ATX specs. The results are below. After working around two minutes on the configuration listed below, the over power protection entered in action, shutting down the power supply. Nice.

Input	Maximum
+12V1	17 A (204 W)
+12V2	17 A (204 W)
+5V	25 A (125 W)
+3.3 V	25 A (82.5 W)
+5VSB	2 A (10 W)
-12 V	0.5 A (6 W)
Total	617.0 W
% Max Load	154.3%
Room Temp.	47.1º C
PSU Temp.	55.8º C
AC Power	792.0 W
Efficiency	77.9%
AC voltage	106.9 V
Power Factor	0.997

Main Specifications

SilverStone Nightjar 400 W power supply specs include:

• Nominal labeled power: 400 W.
• Measured maximum power: 617 W at 47.1º C.
• Labeled efficiency: Between 82% and 86%, 80 Plus Bronze certified
• Measured efficiency: Between 84.8% and 87.2% at 115 V (nominal, see complete results for actual voltage).
• Active PFC: Yes.
• Modular Cabling System: No.
• Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector.
• Video Card Power Connectors: Two six/eight-pin connectors on one cable.
• SATA Power Connectors: Six in two cables.
• Peripheral Power Connectors: Six in two cables.
• Floppy Disk Drive Power Connectors: Two in two cables.
• Protections: Over voltage (OVP, not tested), over current (OCP, tested and working), over power (OPP, tested and working) and short-circuit (SCP, tested and working).
• Warranty: Three years.
• Real Manufacturer: FSP
• http://www.fsp-group.com.tw
• More Information: http://www.silverstonetek.com
• Average price in the US*: 170.00.

* Researched at Newegg.com on the day we published this review.

Conclusions

SilverStone Nightjar 400 W is a superb power supply, using a high-end design, based on a LLC resonant primary and DC-DC converters on the secondary. This allowed to this power supply to deliver up an impressive 617 W during our tests (due to its highly overspec’ed components), present very high efficiency between 85% and 87% (when pulling up to 400 W), voltages very close to their nominal values (below 3% of their nominal value), low noise and ripple and all protections working fine, protecting your equipment.

The absence of a fan makes this unit to be completely mute, combining with applications where silence is a must, like home theater PCs (HTPCs).

The only drawback – and this is a huge one – is its price. USD 170 for a 400 W power supply? No, thank you.