Review Index:

SilverStone Nightjar ST50NF 500W Fanless Power Supply Review

Author: Lee Garbutt

Load Regulation, Line Regulation and Cross-Loading

DC Output Load Regulation

To simulate real world and maximum loading conditions, the SilverStone Nightjar 500W Fanless PSU was connected to the load testers and supplied with a constant 115 VAC. In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads.

The ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances now for the +12V outputs. I have also included a second table of expanded tolerances (±1% to ±6%) for reference.

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The following tables list the DC voltage results at the different loads for the Nightjar 500W Fanless PSU while operating on 115 VAC, 60 Hz.

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The PSU produced excellent load regulation on all of the DC outputs across a broad range of loads. All of the outputs stayed within the advertised ±3%, even when delivering 500 watts; very good!

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DC Output Line Regulation

In this test we are interested in seeing how well a PSU can maintain the various output voltages while the AC input line voltage changes. In the previous Load Regulation test, the AC line voltage was held constant at 115 VAC. Now we will look at how much the DC outputs change as the load is held constant and the AC line voltage is changed from 120 VAC down to 90 VAC.

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The Line Regulation test was performed with the combined DC loads set to 375W. The AC input voltage to the power supply (via the Extech power analyzer) was adjusted using a Powerstat variable autotransformer; virtually no measurable change in the DC outputs.

Cross-Loading Test

PC switching mode power supplies provide multiple DC output voltages. Ideally, the total load should be distributed across all the main outputs (+3.3V, +5V, +12V). This means that the combined +3.3V and +5V load should be proportional to the combined +12V load – as one increases, so should the other. Unfortunately, this is not always the case, especially in newer PCs that predominately use +12V and may put only minimal loads on the +3.3V and/or +5V rails.

Cross-loading refers to imbalanced loads. If a PC pulls 400W on the +12V outputs and only 20W (or less) on the combined 3.3V and +5V outputs, the resulting voltage regulation may suffer.

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In the first test we put a heavy load on the +12V output and a light load on the remaining outputs. The ST50NF PSU had no problem delivering 36A on the +12V rail under these conditions. Even with this imbalance, the voltages all stayed well within spec.

In the second test we reversed the cross-load and placed a heavy load on the +3.3V and +5V outputs with a light load on the +12V rail. Once again, the PSU passed this test without problems and all the voltages remained well within spec.

May 1, 2012 | 01:09 PM - Posted by Rusty (not verified)

Could you use this setup and turn it into a watercooled unit by adding some heat pipes or something?

May 1, 2012 | 04:32 PM - Posted by biblicabeebli

The answer to your question is "Yes, probably?" but the question itself misses the point _entirely_.

IT IS A FANLESS POWER SUPPLY! It is designed to cool itself Without Additional Cooling!

May 1, 2012 | 06:04 PM - Posted by Rusty (not verified)

"Requires forced airflow (case fans) to operate at max output"

May 2, 2012 | 02:42 PM - Posted by biblicabeebli

I think you were trying to make the following point??:
Most power supplies do not have the beefy heat sinks this fanless model has. The application of water blocks etc. would normally be a complete pain, but here we have big, flat chunks of metal to play with, making it bunches of easier.

May 1, 2012 | 08:38 PM - Posted by Lee Garbutt

Yes, you "could" but why even go that route...  If you don't need fanless then just get a good PSU with a quiet fan.

To watercool the ST50NF, you could cut sections of copper tubing and press them into the PSU's large finned heatsink.  Connect the tubes in parallel and add them into your PC's watercooling loop.  Or take a couple old CPU/GPU waterblocks and bolt onto the PSU's heatsink (after drilling and tapping). 


May 2, 2012 | 06:21 AM - Posted by rrr (not verified)

Awful value. You can get Seasonic X-460 or Kingwin Stryker/SuperFlower Golden Silent 500W, both of which are:

-more efficient
-have better ripple suppresion than this unit.

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