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Thread: Just bought Silverstone SX650-G - PG signal low

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    Arrow Just bought Silverstone SX650-G - PG signal low

    Hello, I actually just bought one of these new off of Amazon. It is my first SFX power supply. I always test psu before I use them with my tester. (And actually I don't even have the case yet for use with this psu so I can't really test it on a motherboard at this moment.)

    So when I tested it all the voltage indicators were within 0.1 v and looked green across the board but the tester was still beeping. The only value that wasn't in the correct range was the PG. It was at 80ms. I read that the tester is looking for between 100ms and 500ms.

    I am wondering if 80ms is bad enough to return the unit?

    Thank you for any advice!
    Last edited by Jon Gerow; 2 Weeks Ago at 01:38 AM.

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    Whether or not the PS Good signal is going to work with your motherboard completely depends on whether or not it works with your motherboard.

    We can't tell you if it's going to work or not. Yes.. the timing is low. But does it work with your motherboard?

    The OP's SX650G uses the same SITI PS224 many other PSUs also uise.

    https://www.tomshardware.com/reviews...-psu,5692.html
    Last edited by Jon Gerow; 2 Weeks Ago at 04:10 PM.

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    Thank you for the reply! My motherboard is currently in use connected to an ATX psu. I wasn't planning on removing it until I get my new SFF case.
    But, if I were to take out my ATX psu and hook up the Silverstone would the indication that it doesn't work with my motherboard be that it just doesn't turn on? Are there other indicators that wouldn't show themselves until the PSU is under high load?

    Is there danger of damaging components when powering on with such a low timing?

    (Sorry for all the questions. I am reading through the forums but it's hard for me to understand some of these things.)

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    Quote Originally Posted by SeaDaddy View Post
    Thank you for the reply! My motherboard is currently in use connected to an ATX psu. I wasn't planning on removing it until I get my new SFF case.
    But, if I were to take out my ATX psu and hook up the Silverstone would the indication that it doesn't work with my motherboard be that it just doesn't turn on? Are there other indicators that wouldn't show themselves until the PSU is under high load?

    Is there danger of damaging components when powering on with such a low timing?

    (Sorry for all the questions. I am reading through the forums but it's hard for me to understand some of these things.)
    It would power on, but not POST.

    No damage.

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    https://en.wikipedia.org/wiki/Power_good_signal

    "The ATX specification requires that the power-good signal ("PWR_OK") go high no sooner than 100 ms after the power rails have stabilized..."


    Why bother to have a delay? perhaps to avoid

    "
    Cheaper and/or lower quality power supplies do not follow the ATX specification of a separate monitoring circuit; they instead wire the power good output to one of the 5 V lines."
    Last edited by ashiekh; 2 Weeks Ago at 03:58 PM.

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    Quote Originally Posted by ashiekh View Post
    https://en.wikipedia.org/wiki/Power_good_signal

    "The ATX specification requires that the power-good signal ("PWR_OK") go high no sooner than 100 ms after the power rails have stabilized..."


    Why bother to have a delay? perhaps to avoid

    "
    Cheaper and/or lower quality power supplies do not follow the ATX specification of a separate monitoring circuit; they instead wire the power good output to one of the 5 V lines."
    Those would be REALLY cheap designs.

    Every PSU from a reputable brand that I have seen uses a supervisor IC that supports a proper power good signal pin.

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    Quote Originally Posted by Jon Gerow View Post
    It would power on, but not POST.

    No damage.
    Thank you. This is the information I was looking for. I have a two week window for a return and my case was shipped out yesterday so hopefully I can assemble it and test in time.

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    My guess is that a replacement will be the same and that the original will work fine.

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    Quote Originally Posted by ashiekh View Post
    My guess is that a replacement will be the same and that the original will work fine.
    Not necessarily.

    Remember, the housekeeping IC isn't getting/giving raw "data". Signals are manipulated through resistors. You change OCP by using different OPAMPS. OVP, UVP, etc. figures are manipulated by resistors, for example. You look at a supervisor IC data sheet and see that UVP is only 9V and "assume" that it's a crappy IC, but really, you have to change that value before it gets to the IC so it sees a higher value, like 11V, as 9V. Just like how you don't change OCP by re-programming the IC.

    I ran into this a while back while at BFG with a batch of bad resistors. They were labeled one thing, but they were actually of a different resistance. This resulted in an out of spec power good signal. This could be something similar as a defective resistor could have the wrong resistance and throwing off the value of the power good signal.

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