Hot Test Results (~45°C Ambient)

The energy conversion efficiency of the SilverStone Nightjar NJ700 was almost entirely unaffected by the high ambient temperature of our hotbox, with the efficiency dropping a mere 0.25% average across the entire load range. This, in conjunction with the lack of any active cooling, suggests that the active components are both oversized and designed so as to greatly resist thermal stress.

Under these operating conditions, the surface temperature of the SilverStone NJ700 reaches levels that would be painful for most people to touch. Nevertheless, the internal temperature of the unit does not get high at all. As a matter of fact, both the primary and secondary side heatsinks stayed a bit cooler than what actively cooled PSUs with such a power output can attain at maximum load.

Cold Test Results (~22°C Ambient) Power Supply Quality & Conclusion
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  • coolkwc - Wednesday, December 8, 2021 - link

    Passive PSU is just pointless. A 12cm fan with 800rpm is easy enough to let the unit stay much cooler without any noise.
  • Oxford Guy - Thursday, December 9, 2021 - link

    Until it clogs with dust. Cleaning a PSU is a pain, especially with a complex water loop.
  • mindless1 - Monday, January 17, 2022 - link

    You have this backwards, in most cases. In order to not draw in dust through the passively cooled PSU, the case must have positive pressurization, placing more audible (per same amount of noise) intake fans forward (and on top) in the case, assuming typical rear-out airflow pattern.

    If someone cares about dust, they minimize its entry into the case instead, using filter media. You could strap a filter onto the PSU too, but this is someone already committed to using filters so would certainly filter other intake areas as well, so there would be minimum dust getting into the PC to enter the PSU, in the situation of a fan cooled PSU.

    Further, not having to rely on the case intake fans to passively cool the PSU, means they can run at lower RPM so these more audible fans (per amount of noise created) are creating less noise.

    I don't even understand your post. If cleaning is so complex because you didn't design with cleaning in mind, then why on earth would you go with a passive PSU, which is all the more subject to needing minimum dust for good cooling, instead of using appropriate case filtration? Seems like multiple design mistakes in a row if you are placing priority on system longevity, but I concede some will just chase the ghost of quiet, so they can make their own noise instead from other things, which is kind of strange that the user can be the only entity making noise but whatever.
  • Lucky Stripes 99 - Saturday, December 11, 2021 - link

    In an otherwise silent room, you'd be amazed at what you can hear. After building a silent PC, I started picking up on some barely audible whine from my monitor. Never noticed it before, even with very quiet PCs prior.
  • Oxford Guy - Saturday, December 25, 2021 - link

    Some people live in noisy cities, in buildings that aren’t great at blocking noise. Research has also found that regular long-term subway commuting (i.e. NYC) causes serious hearing damage. That many claim things are quieter than they are can be partially explained by differences in the state of their hearing and the ambient level beyond what the equipment produces.
  • Wrs - Sunday, December 26, 2021 - link

    Certainly possible, but ambient noise levels in a home environment are unlikely to be related to hearing damage. (I've been in thousands of homes. The vacuum and blender and occasional kid's scream are probably the loudest things but those aren't chronic.) It's more that comparable electronic parts can make orders of magnitude more or less perceptual noise. This goes for both fans and coil whine because of differing human sensitivity toward different frequencies. We're about 1000x more sensitive to 3000 Hz than to 200 Hz. Pretty much when you see hearing damage around 3000 Hz it's listening to loud music or long-term exposure to city traffic or a loud workplace. Then there's of course wax buildup - the removal of which increases sensitivity and lowers the threshold for hearing damage.

    So yeah, fanless PSUs can be way louder than fanned ones if they're not hardened against coil whine. But unless you're using server fans no computer component ought to be in the same sentence as hearing damage.
  • Oxford Guy - Monday, December 27, 2021 - link

    Why is hearing damage the point here? The main point is being able to enjoy one's environment. Noise pollution impedes that.

    Also, people with tinnitus can find that sound levels well below damaging can aggravate tinnitus. I am very sensitive to computing equipment. Enough exposure to a gaming machine and hiss tinnitus transforms into a warble that's extremely problematic when it comes to getting a decent night's sleep. Therefore, the damage from aggravated hearing can come from lack of high-quality sleep and the stress of irritating phantom noise.
  • Wrs - Tuesday, December 28, 2021 - link

    @Oxford Guy because you keep bringing up hearing damage, from subways or headphones. I do not know what subways have to do with computing equipment, but I do understand if computing equipment is loud enough, then using open headphones to drown them out can lead to hearing damage. I'm just saying most modern fanned consumer PSUs are magnitudes away from loud enough to cause that. I'll of course make exception for defective, or poorly designed, or server PSUs.

    Hey, I appreciate you bringing up concerns of those suffering significant tinnitus, which I can't comment on as have no experience or training. But let's not blanket project those concerns to buying advice for all users, as around 95% don't have it (depends on how severe the cutoff).

    And then with this clogs-with-dust comment -- do you have something personal against PSU fans? As I understand the radiator in an open loop is far denser and thus clogs with dust much sooner than tower fins or a PSU fan which is essentially a downdraft cooler with an intake grille, one of the easier things to clean in a modern case as you can just vacuum the intake from the exterior.
  • mindless1 - Monday, January 17, 2022 - link

    Apparently potential buyers can't enjoy their environment and are always chasing the ghost of zero noise. I enjoy my environment equally well from the very subtle sound of air from low RPM fans. If I were engaged in an activity that produces a lot of heat like gaming, then my focus would be on the game, certainly not distracted by low RPM fans, but if I were distracted it would be from the more powerful intake fans needed to keep a passive PSU cool enough.
  • Lucky Stripes 99 - Saturday, December 11, 2021 - link

    I'd love to see highly efficient quiet power supplies like this in the flex ATX form factor. I replaced the stock PSU in my mini ITX case with a fanless 12V DC-DC PSU fed by a 216W laptop brick. It is silent, but it took some soldering and drilling to make everything work.

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