Conclusion

SilverStone's PSU division places a lot of their R&D efforts into the advancement of small form factor systems, and the Nightjar NJ450-SXL is testament to that fact. The Nightjar NJ450-SXL is the first (and currently only) advanced fully passively cooled PSU in SFX form factor, designed to power truly quiet SFF PCs.

The electrical performance of the Nightjar NJ450-SXL is impressive, especially for a passively cooled PSU of this size. We recorded excellent power quality figures, with the PSU showing outstanding voltage line stability. There is very low voltage ripple on all lines, with Enhance designing the platform so as to perform best when it's normally loaded. The PSU easily meets its 80Plus Platinum efficiency requirements at both common input voltages and, as we expected from a passively cooled unit, it is measurably more efficient than the average 80Plus Platinum-certified PSU.

SilverStone backs the NJ450-SXL with a three-year warranty, which is acceptable but not really impressive by today’s standards. Nevertheless, the design and overall quality of the PSU appears to be excellent. Enhance did not cut any corners, performing an exceptional assembly job and using top quality parts all around. We do not foresee any quality-related issues, except perhaps from cases where the PSU may remain significantly and continuously loaded for long periods of time at high ambient temperatures.

When using a passively cooled PSU, there are certain implications. The major point that requires consideration is the fact that the heat generated by the PSU (i.e. its thermal losses) will be released inside the system itself, whereas typical PSUs would actively vent most of that heat to the outside of the case. This means that the system itself will get hotter and may require better cooling in order to sustain its overall performance. Even the PSU’s overall performance will degrade if the ambient temperatures inside the case rise, impacting its own efficiency and longevity. This will probably not be a problem with modern systems that are built with efficiency in mind, but the specifics of this must be considered and weighted by the system’s builder in building a balanced system. After all, it would not make any sense to use a passively cooled PSU only to replace it by another noise source, such as additional case fans.

With the Nightjar NJ450-SXL SilverStone is seeking to satisfy the craving of those who are obsessed with absolute silence, allowing experts to design truly tranquil living room entertainment systems. The performance of the Nightjar NJ450-SXL is excellent and will leave nobody disappointed. However, the design of a truly silent PC requires expertise and the PSU alone is but a small factor. For example, the noise coming from typical gaming GPU will greatly exceed that of the PSU, making its purchase pointless to begin with. The Nightjar NJ450-SXL is a specialized product meant to offer advanced users and experts the ability to design near or fully silent systems, but buyers will want to keep in mind that making the most of the passive PSU will require a bit more than a basic level of user/builder experience.

Hot Test Results (~45°C Ambient Temperature)
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  • ingwe - Thursday, April 4, 2019 - link

    This looks like a great PSU overall, but a passive PSU would make me pretty nervous about longevity.
  • Exodite - Thursday, April 4, 2019 - link

    I can only offer anecdotal support but I don't think you should worry about that, as long as the PSU itself is of good quality.

    I've been using the same Seasonic SS-FL460 (a fanless 460W, Gold-rated unit) since 2011 and while it's still powering the same i7 2600K I bought along with it it's scaled perfectly all the way up to a Vega 56, 4 HDDs and a SSD.

    I don't game 24/7 by any means but even when stressing the unit as far as my setup allows (Prime95 + FurMark) it doesn't get particularly warm.

    Unfortunately my particular unit isn't the perfect example of the benefits of fanless PSUs as it has some audible electrical noise under particular loads, so there's that. :)
  • jeremyshaw - Thursday, April 4, 2019 - link

    Audible electrical noise is the exact reason I sold off my last Seasonic passive PSU. Mine made more noticeable noise than the fan did on another Seasonic PSU. Unacceptable, IMO, so I actually haven't bought another Seasonic since then (apparently a good choice, since they have since languished in PSU design, even if their quality remains reasonably high).
  • Exodite - Thursday, April 4, 2019 - link

    Completely understandable.

    I'm in the market for a new desktop later this year and if I end up replacing the chassi and PSU as well it probably won't be with a fanless model. Not because of any issue with passive cooling but rather the noise.

    I'm still interested in Seasonic primarily I admit but since I value silence and the electrical noise of the new models are an unknown to me I'm inclined to go with a traditional solution.
  • FreckledTrout - Thursday, April 4, 2019 - link

    I have a Seasonic Prime Ultra 850 Titanium SSR-850TR in my desktop build with a Ryzen 1800 and a GTX 1070. Having 850 watts its complete and utter overkill but it's basically fanless unit in hybrid mode for 99% of my usage and being Titanium I don't lose much efficiency running it at 25-40% of max wattage. It also has zero electrical noise that can make out even when I put me ear up to it with the fan not running I hear nothing.
  • Exodite - Thursday, April 4, 2019 - link

    Thank you, that's good information!

    If I do switch PSUs it's likely going to be a Titanium unit, for the 10% efficiency minimum. Hitting ideal efficiency under load is usually easy enough at any load from 25-100% but I'm hoping to improve my efficiency at idle and basic desktop use too.

    A 650W Titanium unit should still be 90% efficient at 65W and that's not an unrealistic figure at the desktop, I think?

    At least that's about what I'm seeing now, though obviously a more modern platform may well draw less power.
  • daniel78R - Thursday, April 4, 2019 - link

    I have a Corsair SF600, in a FractalDesign Node 202 powering a Ryzen 1600X (with Scythe Big Suriken - modified) and GF 1060 and unless I start a game, the PSU does not start the fans, and even when it starts, it is way less noisy than CPU or GPU fans, and they are not very loud either
  • nagi603 - Monday, April 8, 2019 - link

    > At least that's about what I'm seeing now, though obviously a more modern platform may well draw less power.

    Not necessarily, especially for GPUs. (1080 vs 2080 is quite a jump, 180 to 215W) The bump in core count has not resulted in lower idle draws either.
  • emn13 - Wednesday, April 10, 2019 - link

    Although the electrical noise is major irritant for those that suffer from it, it's by no means universal, and it's not just one or two manufacturer's that have this problem. I'm pretty sure it's also not even really model-specific in the sense that even within the same model some batches are problematic, and other's aren't.

    Which means you might want to simply resign yourself to trying several ones, and sending bad ones back, rather than relying on trying to divine some pattern from the online reviews, many of which don't mention this at all.
  • tonyou - Sunday, April 7, 2019 - link

    PSU electrical noises are usually high frequency noises and travel by air, so with NJ450-SXL's external aluminum heatsink shell having no vents, it actually helps reduce those noises better than any PC power supply ever could.

    If silence is your priority, you should give NJ450-SXL a try.

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