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Thread: Can using a 1200W PSU at low load levels (~5%/50-60W) for days/weeks cause damage?

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    Default Can using a 1200W PSU at low load levels (~5%/50-60W) for days/weeks cause damage?

    As the title suggests, I would like to ask if using a 1200W PSU for example the beQuiet Dark Power Pro 11 1200W at very low loads for long perios of time damage the PSU?

    I am asking because the PC may sit idle for days/weeks on end roughly consuming between 50-60 W and I read on Tom's that running a (1200W) PSU at such a low load can indeed cause damage. Is this true?

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    No. It's fine.

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    Quote Originally Posted by Mouryou View Post
    I read on Tom's that running a (1200W) PSU at such a low load can indeed cause damage. Is this true?
    do you have a link ?

    The only drawback that I know , that most psu wont be at their rated effecieny (slightly lower) at lower than 10% load but at such low wattage that is a very insignificant outcome
    CPU: i7 9700K / Motherboard: Gigabyte z390 Aorus Pro Wifi
    RAM: 2 x Ballistix 8GB DDR4 @3000MHz GPU: ASUS ROG STRIX RTX 2070 Advanced
    SSD: ADATA XPG SX8200 Pro 1TB NVMe / HDD: 3TB WD 30EZRX
    PSU: Corsair RM850i -850w Gold / CPU Cooler: bequiet! Dark Rock Pro 4
    PC Case: CoolerMaster H500P Mesh White /Monitor : Samsung Professional monitor S27B970D
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    Quote Originally Posted by Mezoxin View Post
    do you have a link ?

    The only drawback that I know , that most psu wont be at their rated effecieny (slightly lower) at lower than 10% load but at such low wattage that is a very insignificant outcome
    Yes I have: https://forums.tomshardware.com/thre...-myths.194370/

    Look for "RetiredChief" comment where he states: "On large PSUs, I still recommend You s limit the max size so that Idle power is at least 10 %., Provided you can still stay below the 80% at max load. Reason for the 80% is more a longevity issue than cost savings. By design Very low power is hard on PWM circuits employed in Switching PSU. In fact the Initial Computer Power supplies would go up in smoke if Power output was zero (NO LOAD) - after a few years this was corrected (initially added resistor to provide a bias current - Then added a safty circuit to simply switch PSU off when No load is detected.. May be wrong on this but when the duty cycle becomes close to zero current accually goes very high"

    Is this true or not? Or maybe was it true in the past but is not anymore?

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    Quote Originally Posted by Mouryou View Post
    Yes I have: https://forums.tomshardware.com/thre...-myths.194370/

    Look for "RetiredChief" comment where he states: "On large PSUs, I still recommend You s limit the max size so that Idle power is at least 10 %., Provided you can still stay below the 80% at max load. Reason for the 80% is more a longevity issue than cost savings. By design Very low power is hard on PWM circuits employed in Switching PSU. In fact the Initial Computer Power supplies would go up in smoke if Power output was zero (NO LOAD) - after a few years this was corrected (initially added resistor to provide a bias current - Then added a safty circuit to simply switch PSU off when No load is detected.. May be wrong on this but when the duty cycle becomes close to zero current accually goes very high"

    Is this true or not? Or maybe was it true in the past but is not anymore?
    The guru has spoken

    No. It's fine.
    Jon Gerow
    CPU: i7 9700K / Motherboard: Gigabyte z390 Aorus Pro Wifi
    RAM: 2 x Ballistix 8GB DDR4 @3000MHz GPU: ASUS ROG STRIX RTX 2070 Advanced
    SSD: ADATA XPG SX8200 Pro 1TB NVMe / HDD: 3TB WD 30EZRX
    PSU: Corsair RM850i -850w Gold / CPU Cooler: bequiet! Dark Rock Pro 4
    PC Case: CoolerMaster H500P Mesh White /Monitor : Samsung Professional monitor S27B970D
    DAC: Audioengine D1 /Speakers : Focal Bird 2.1 / Headphones: Sennheiser HD 380Pro / B&W PX

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    Quote Originally Posted by Mouryou View Post
    Yes I have: https://forums.tomshardware.com/thre...-myths.194370/

    Look for "RetiredChief" comment where he states: "On large PSUs, I still recommend You s limit the max size so that Idle power is at least 10 %., Provided you can still stay below the 80% at max load. Reason for the 80% is more a longevity issue than cost savings. By design Very low power is hard on PWM circuits employed in Switching PSU. In fact the Initial Computer Power supplies would go up in smoke if Power output was zero (NO LOAD) - after a few years this was corrected (initially added resistor to provide a bias current - Then added a safty circuit to simply switch PSU off when No load is detected.. May be wrong on this but when the duty cycle becomes close to zero current accually goes very high"

    Is this true or not? Or maybe was it true in the past but is not anymore?
    So the words of ONE INDIVIDUAL that responded to a post EIGHT YEARS AGO has you scared?

    He's talking about pretty old PSU designs. Designs used almost 20 years ago on PSUs that typically output no more than 500W.

    The Dark Power Pro is an LLC topology with DC to DC for the +3.3V and +5V. You can low load it. You can cross load it. You're not hurting it.

    While the low load efficiency is bound to be HORRIBLE at lower (< 5%) loads on a 1200W power supply, it's not going to hurt the power supply.

    In the future, you'll see more PSUs that use a PWM controller that switches from LLC mode to burst mode; but this is in an effort to improve low load efficiency, not to ensure component longevity.

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