PSU wattage and energy bills

Discussion in 'General Hardware' started by Pzykotik, May 7, 2014.

  1. Pzykotik

    Pzykotik Ancient Guru

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    This is going to sound stupid, but what are the energy implications of "bigger" power supplies?

    It figures that the bigger a power supply is the more energy it will pull from the mains... But is that necessarily true? I mean, I know there are differences in the efficiency etc of supplies and it makes sense that if the components in a PC only draw X amount of power, then the PSU will only use X amount... Otherwise, what happens with the excess energy...

    Can anybody make sense of things for me?
     
  2. Deathchild

    Deathchild Ancient Guru

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    A psu with 90% efficiency will pull 550w from the wall if the required load is 500.

    An 80% psu will pull 700w from the wall if the required load is 500. It's the components that make up the power load, not the psu itself.. it's just there to provide it.

    Nothing happens with the excess energy (there is no excess energy), bigger psus are just able to supply more if needed than their counterparts.
     
    Last edited: May 7, 2014
  3. Pzykotik

    Pzykotik Ancient Guru

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    Good, that's what I thought. Even if I didn't make much sense when asking the question.

    I sometimes wonder how I've forgotten all my high school science classes. Too much tinkering with Windows Server...

    Thanks!
     
  4. Deathchild

    Deathchild Ancient Guru

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    :D Yeah no worries.
     

  5. Pinocchio

    Pinocchio Member Guru

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    GPU:
    msi hawk 5770
    Required load is 500w

    90% efficiency: 500/0.9 = will pull 555w

    80% efficiency: 500/0.8 = will pull 625w

    Is my math wrong ?
     
  6. Extraordinary

    Extraordinary Ancient Guru

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    Efficiency aside, a 1000w PSU will pull no extra from the wall than a 500w PSU, if you are only pulling 200w load

    That's my understanding of it
     
  7. Barry J

    Barry J Ancient Guru

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    GPU:
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    I use at full load about 50% of what my PSU can output but at 50% I get the best efficiency 93% @ 700w from my PSU that's one of the reasons why I went bigger the other was never worrying about what hardware I can use without changing PSU .
    It cost me more to buy and it is more than I need, but it costs me less to use.

    http://www.techpowerup.com/reviews/EVGA/SuperNOVA_G2_1300/6.html
     
    Last edited: May 7, 2014
  8. -Tj-

    -Tj- Ancient Guru

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    Will you get that RPGgamesplayer deal?,

    Imo that would save you more money, i7 920 OC'ed consumes at least 1x more power then highly Oc'ed 4770K

    + extra perf. up to 100% for sure, I mean I saw min 150%-200% vs my old Oc'ed q9450@ 3.6ghz.
     
  9. Pzykotik

    Pzykotik Ancient Guru

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    I was really lucky (who knew being online so often would pay off), and I did get the deal.

    The machine feels VERY quick after build. The move to Windows 8 helps quite a bit I think, and knowing that it'll save me money is great news! I got a new PSU from Jonny Manc as well, and didn't know if it was worth me changing down to it (1250W to 750W).
     
  10. -Tj-

    -Tj- Ancient Guru

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    Yeah nice, have fun :nerd:
     

  11. scoter man1

    scoter man1 Ancient Guru

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    I think that's only relatively true. I think I remember seeing a curve from a psu where at certain usage percentages, it's more efficient than others.

    For example <10% was like 82% efficient
    between 10 and 90 was 87% efficient
    and above 90% was lower again.

    The bronze/silver/gold/platinum rating is given to whatever is the lowest efficiency, I think.
     
  12. Extraordinary

    Extraordinary Ancient Guru

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    Yea that makes sense, I was trying to put into words that a 1000w PSU doesn't necessarily mean it will cost more than a 500w PSU to run if your system only uses 200w

    The 1000w gold efficiency rated PSU could be cheaper to run than the 500w non-efficient PSU
     
  13. k3vst3r

    k3vst3r Ancient Guru

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    GPU:
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    tends to be above 20% to 100%

    below this an might be little more inefficient
     
  14. Pzykotik

    Pzykotik Ancient Guru

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    Totally.

    [​IMG]


    My CPU is most efficient around the 50% mark (91%), dropping to 88% at highest power draw.
     
  15. Anarion

    Anarion Ancient Guru

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    You are barely hitting that 20% with your rig.
     

  16. Pzykotik

    Pzykotik Ancient Guru

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    Eh? 20% is 250W... I recon I'm using about 500...
     

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