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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  • Oxford Guy - Monday, December 27, 2021 - link

    I tracked down a review of Seasonic PSUs (SS-1050XP3 & SS-1200XP3) from this site for those claiming fans are no problem in PSUs. The first red flag is the lifespan of the fan:

    'Seasonic went with a San Ace 9S1212H403 120mm fan in both of their newest models.

    The life expectancy of this fan is 40,000 hours, a rather mediocre rating for similar devices, translating to about 4.5 years of 24/7 use at 60°C, albeit this rating also is for a free, unobstructed air path (zero static pressure, max airflow).'

    4.5 years is a lot less than infinite, since a fanless PSU doesn't have a fan lifespan issue.

    Then, we get to the noise, which is a far far cry from 'silent', even in the cold tests:

    SS-1050XP3 results, cold test (decibels at the specified wattage):

    'The 120mm fan can be clearly heard at just 40% load and its speed climbs rapidly as the load increases, surpassing even 50dB(A) at very high loads. At such noise levels, the Platinum SS-1050XP3 can be clearly heard from rooms away.'

    400 — 32
    500 — 36
    600 — 38
    700 — 42
    800 — 46
    900 — 48
    1000 — 50
    1050 — 51

    SS-1050XP3 results, hot test:

    200 — 34
    300 — 37
    400 — 39
    500 — 44
    600 — 46
    700 — 49
    800 — 51
    900 — 53
    1000 — 55
    1050 — 55.5

    I guess I was being too kind by talking about the concern being a PSU that's loud enough to be heard from rooms away. Ear-splitting is apparently another tier here:

    'The behavior of the cooling system remains similar with the PSU inside our hot box, with the exception that the fan is even more aggressive, starting at just 20% load and with its speed climbing rapidly as the load increases. At 50% load, under such conditions, the Seasonic Platinum SS-1050XP3 already is a loud PSU, with the sound pressure reaching ear-splitting levels at >80% load.'

    SS-1200XP3 cold test:

    600 — 39
    700 — 41
    800 — 44
    900 — 47
    1000 — 49
    1100 — 52
    1200 — 52

    SS-1200XP3 hot test:

    300 — 37
    350 — 39
    400 — 40
    500 — 43
    600 — 46
    700 — 48
    800 — 51
    900 — 52
    1000 — 54
    1100 — 56
    1200 — 56

    PSUs like those sell fanless units to people like me.
  • Oxford Guy - Monday, December 27, 2021 - link

    Sound levels are from 1 metre away. Forgot to mention that.
  • Wrs - Tuesday, December 28, 2021 - link

    This is silly. Not only are these 5 year old designs, but can you explain how someone worried about noise would be drawing 1000W? The PSU has a fan to cool ~120W, but what's cooling the 1000W? If I were super worried about noise, like using a PC in a broadcast studio without mic noise cancellation, I would probably get a system of no more than 250W typical, with a 650W+ hybrid PSU where the fan doesn't even spin at 250W. Effectively fanless in production, turns on during emergency/off hour loads to save the PSU.

    I'm not worried one bit about fan life expectancy these days. It's trivial to find a start-stop fan PSU. Mine from 11.5 years ago is ball bearing and fully start-stop, though that was rare back then. These days mainstream FDB is used with hysteresis. Remember there's capacitor life expectancy in a PSU and mobo. For every 10C delta, expect a doubling or halving of life. A PSU intake is not going to be 60C, which is scalding hot. A modern case has the PSU draw air straight from ambient
  • Oxford Guy - Tuesday, December 28, 2021 - link

    'This is silly.'

    I'm amazed you're still at it.
  • Wrs - Tuesday, December 28, 2021 - link

    Side note. Human speech typically runs 50dB at home, 60dB in public. I'd hope neither is ear-splitting!

    Here's a PSU that measures 20dB at 1300W. The review is almost 4 years old, but the unit was well ahead of its time, close to the pinnacle of efficient design, you could say. Uses technologies still not commonplace, especially GaN FETS.
  • Oxford Guy - Tuesday, December 28, 2021 - link

    Even quieter is a fanless unit.

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