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Thread: Advantage or Disadvantage of going overkill at PSU

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    Default Advantage or Disadvantage of going overkill at PSU

    my new graphical card (msi 2080 ti trio x) has 2x8pins and 1x6pins power connections, my current psu has only 2, and i really dont wanna use a converter for the third.

    i am planing to upgrade to a rm850x corsair but just found a good deal for 1000w version. almost same price with 850. 850w will probably be more than enough.


    is there an advantage to go overkill at PSUs ?

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    Assuming only capacity is increased (and quality not decreased) then life and reliability may be increase by over-rating; efficiency may also improve and with it the fan noise may be less.

    Notice the liberal use of 'may'.
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    Last edited by ashiekh; 09-07-2019 at 09:39 PM.

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    The worst things:
    1. higher noise in some cases -> higher wattage, higher RPM. Some higher wattage units come with 3000RPM fans, lower wattage ones with 1200RPM for example.
    2. more damage if something goes wrong, worst case with a 1600W unit is this -> https://www.overclock.net/forum/31-p...ulti-rail.html <- that is also happened because the PSU was single rail as well. Wich means 100% of power on every single cable. Multi Rail just splits it like Breakers in your box.
    3. You waste money. Depending on the PSU, it can be 30 or more.



    But either way, even 850W is bullshit for a non HEDT System and I wouldn't go for more than 750W.
    Hell, even 550W should be enough for that, if we are talking about a normal Mobile/Desktop System (AM4, LGA115x), 650W "to be on the safe side".

    Also what's your current PSU?
    Depending on that it might be possible to use the GPU anyway, as its possible that it does not need the third (6pin) connector and works with 2x8.
    BUT: not all PSU are recommended to be used in that setup...

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    tried to use only 2 8 pins and didnt work. according to ppl with same card it draw around 300w.

    my current psu is corsair GS700, acconding to sites which calculates max draw, system will use 500-550w, original plan was to get a 750w. i really dont know if i need 100 more or not.

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    Quote Originally Posted by lemartes View Post
    tried to use only 2 8 pins and didnt work. according to ppl with same card it draw around 300w.

    my current psu is corsair GS700, acconding to sites which calculates max draw, system will use 500-550w, original plan was to get a 750w. i really dont know if i need 100 more or not.
    If the RM1000 is that cheap, just get the RM1000.

    To counter Mr. Payne's arguments:

    1. It is true that a higher wattage PSU will have a fan with a higher maximum RPM fan because more wattage = more heat. This can throw the whole fan curve off because a higher RPM at the high end also means higher RPM at the low end since the number of windings need to be increased to achieve the higher RPM and that then requires higher voltage to start the fan.

    That said, while most PSU's with DC controlled fans will just increase the voltage to the fan as the PSU gets hotter without any consideration of the RPM, the RM series (and higher) use an MCU to control the fan and takes into consideration the load as part of it's equation. It has a table programmed into it for when the fan should spin, at what RPM and for how long. So for you this should be no issue.

    2. This much damage is going to occur on any PSU that's about 750W and higher. It can and does happen if there's a failure, but it's very rare.

    3. You're not wasting money. You said it's the same price.

    And as for the "efficiency curve" ashiekh showed: That's for an older style double forward front end PSU that doesn't take load into consideration. The RMx has a LLC resonant mode topology and it's efficiency "curve" is relatively flat.

    Any noise and efficiency concerns can be addressed here: https://cybenetics.com/d/cybenetics_j21.pdf

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    thank you for your detailed answer.

    at this point my only concern is even on this forum it says ts better to buy a units with newer release date.

    850W is probably a 2018 release while 1000W one isnt renewed and a 2015/2016 release.

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    I think you might have misunderstood what you read.

    Older PSUs use older technology. Example: Buying a Seasonic S12II today.

    Discontinued PSUs that are still being sold as new could have been sitting on the shelf a long time and drained caps in hot temperatures don't age well. Example: Buying a Antec NeoEco today.

    And RM1000x is neither old tech nor is it discontinued, so the amount of time it's been on the market is a moot point.

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    Quote Originally Posted by Jon Gerow View Post
    And as for the "efficiency curve" ashiekh showed: That's for an older style double forward front end PSU that doesn't take load into consideration. The RMx has a LLC resonant mode topology and it's efficiency "curve" is relatively flat.

    Good to know, thanks.

    but what do you mean by "that doesn't take load into consideration"

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    Quote Originally Posted by ashiekh View Post
    Good to know, thanks.

    but what do you mean by "that doesn't take load into consideration"
    The switching frequency remains constant during all loads with a double forward topology.

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    Quote Originally Posted by Jon Gerow View Post
    The switching frequency remains constant during all loads with a double forward topology.
    Then how do they feedback(adjust) voltage? duty cycle?
    What about other non-llc topologies like ACRF?

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