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Thread: Semi-passive in this, and not only in this psu

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    Default Semi-passive in this, and not only in this psu

    Why in this power supply https://www.silentiumpc.com/pl/produ...-m2-gold-550w/ semi-passive mode is specified by RPM with load of the power supply? I noticed that in not only this PSU, but also in some other power supply. So here's my question - If im thinking good, why Semi-passive mode in Supremo m2 (most popular brand in Poland) isn't definited by temperature? Or maybe i'm wrong, and it's just a special marketing play for consumers.

    Thanks in advance!

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    It's defined by temperature.

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    This power supply doesn't have any semi-passive mode. Where are you seeing that?

    To answer your point, the fan chart doesn't say RPM is defined by load. It portraits the fan's RPM and also tells what was the PSU's load at that point, but doesn't say they're related to each other. For example, if I put the number of pirates in the world on the Y-axis, and the number of Nicolas Cage movies on the X-axis, it doesn't mean Nicolas Cage movies are killing pirates.

    Like JG says, it's defined by temperature.

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    Quote Originally Posted by Orion View Post
    It portraits the fan's RPM and also tells what was the PSU's load at that point, but doesn't say they're related to each other.

    And yet the measured temperature depends on the load (as well as input temperature) and I would assume the plot is for a given input temperature (perhaps the maximum rated); so I'd definitely say the fan speed and load are correlated, just that there are more factors, namely the input temperature.

    What is somewhat disturbing is that the x-axis is not smoothly divided

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    Last edited by ashiekh; 05-30-2019 at 11:22 PM.

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    Do other power supplies all work like that?(based on temp)

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    Quote Originally Posted by rgbodosk View Post
    Do other power supplies all work like that?(based on temp)
    Most should.
    Some might actually be load regulated but that's rather impractical as it doesn't account for temperature, thus is unnecessarily loud.


    For Semi Fanless you'd want a mixture of both, if possible.

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    I assume most of them if not all them work on temp like said.
    Usually they do a graph that depend on Watt because its more logical to the most of the users.
    You will see sometimes note that the graph base on 25 Celsius degree and may change.

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    Quote Originally Posted by none77 View Post
    I assume most of them if not all them work on temp like said.
    Most. Not all.

    But there's a cost adder for using load. You need op-amps to measure the load and an MCU to calculate the hysteresis. The RMx and up (and the new RM) and the SF Platinum use an MCU that use a formula of load, temperature and duration.

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    Okay, thanks all for answers, and of course it's my fail, because it's not semi-passive. One more question - what if you have FOR EXAMPLE two power supplies. Supremo 550W and 650W. This 550W version will be working with more RPM's when both are loaded about 400W? I am asking because it is often, that the case that a power supply has more power differs only in that, it has higher protections and internal is the same. On many groups, people say, that more power = better temperatures in the same power supply. It doesn't have to be only this case, maybe RMX 550 and 650 or 750 or higher.

    IMO semi-passive mode steered by temperature is simple, because i have been doing a few experiments with opamp + mosfet/relay and thermistor for measure the temperature and it works.
    Last edited by psupply; 06-01-2019 at 07:39 AM.

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    A de-rated power supply will in general last longer, but there are many more factors.

    A cheap de-rated power supply may not last as long as a quality supply that has not been so far de-rated.


    "Everything should be made as simple as possible, but no simpler"
    Albert Einstein

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