Power Supply question

Discussion in 'General Hardware' started by narukun, Jun 25, 2016.

  1. narukun

    narukun Master Guru

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    GPU:
    EVGA GTX 970 1561/7700
    Hey guys, i'm using a SeaSonic Gold 550w, its a very well made PSU. These are the specs:

    [​IMG]

    So.. my PSU just came with 2 of these cables (6+2 pci-e)

    [​IMG]

    Can i connect two 6+2 pci-e with molex cables on the Peripheral - IDE / SATA ports and make work a gtx 970 sli?

    [​IMG]

    I have my setup registered on the left, i have my CPU overclocked to 4.1ghz right now. I dont have any additional pci-e and im using 2 drives (no cd-rom) just a 1tb hdd and 256gb ssd. I dont know if i can really blow my PSU like this.
     
  2. nz3777

    nz3777 Ancient Guru

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    My opinion- That is pushing it but I could be wrong.I would not risk it and just run 1 x gtx 970 until can get something with some more power.

    Seasonic is a very good brand of course!
     
  3. airbud7

    airbud7 Guest

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    GPU:
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    agree with nz3777^....that is a nice PSU with 45amp on single rail/ still you should get 650 or better just to be safe...I could be wrong though seasonic is a very good PSU.
     
  4. vase

    vase Guest

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    GPU:
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    at stock clock (both GPUS and the CPU) you are totally fine. -> http://outervision.com/b/5NuxoO
    overclock and you may get problems pretty quickly.
    whats your cpu vcore? if you can oc to 4.1ghz with 1.25V then you are still fine.

    gpu i cant help because i dont know the overvoltage of nvidia etc...
     

  5. narukun

    narukun Master Guru

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    GPU:
    EVGA GTX 970 1561/7700
    Well i think i'll just try and see hows going, its just for test some games because the other gtx 970 its not mine so it wont be 24/7 use.
     
  6. vase

    vase Guest

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    any chance to measure power draw for you at the moment?
    those thingies cost 10 bucks if you go for the home consumer ones.
     
  7. jura11

    jura11 Guest

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    Hi there

    This PSU should be OK for yours needs,GTX 970 is not power hungry,although OC of the GTX970 can push PSU and I've run 750W PSU with OC 4.2GHz X5670,2 SSD and 6 normal HDD,GTX Titan X OC(1423MHz) and GTX780 OC,PC has been used for rendering like with GPU and CPU(some sort of Hybrid rendering) and never have any issue with my PC,my PSU has been Silverstone PSU

    Right now I'm running too GTX Titan X SC with i7 5820k OC to 4.4GHz,2 SSD and 7 HDD etc and PSU I'm using AX760i

    But agree Seasonic is one awesome PSU,they're still the best PSU on market with Super Flower/Leadex

    Hope this helps

    Thanks,Jura
     
  8. airbud7

    airbud7 Guest

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    GPU:
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    you at 1440p?....if not/ waste of time....could fu*k stuff up for no reason....
     
  9. narukun

    narukun Master Guru

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    GPU:
    EVGA GTX 970 1561/7700
    Well you have a good setup there, but you're using a 750w psu so its definitely fine. Thanks for the info.

    I'm using 1080p but i wanna try some games at 4k with DSR + gtx 970 sli, its just an opportunity that i have right now, because the other gtx 970 its not mine.

    I dont have any of those.. but i dont think im using all the 550w, maybe like 400w as much. I do have my GPU heavily overclocked, i use 130% of power target sometimes with The Witcher 3 + 1531mhz of core clock so i think thats like 261w just for the gpu

    this is the draw just for stock:

    [​IMG]
     
  10. AsiJu

    AsiJu Ancient Guru

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    GPU:
    KFA2 4070Ti EXG.v2
    You can use the peripheral outputs for the second GPU, they're the same +12 V lines as the PCI-E.

    Luckily your PSU is a single-rail design with 45 A output. However given that's split between GPUs, CPU and other devices it may be a bit so-so.
    No harm in trying though, but if you get stability issues I suggest removing the second card until you can upgrade the PSU.

    edit: actually you shouldn't have issues:

    The reference TDP of GTX 970 is 145 W x 2 = 290 W
    The TDP of 3770K is 77 W + overclock = let's assume 100 W for safety.

    That's 390 W combined. Plus peripherals but they don't account for much.

    Your PSU can output 540 W * 0,9 = 486 W from +12 V so should be enough.

    The 0,9 is midway between 50 % and 100 % load efficiency for 80Plus Gold for 230 V VAC:

    https://en.wikipedia.org/wiki/80_Plus

    EVGA lists the TDP as 201 W but that's just the max power draw from 8+6 pin + PCI-E bus I think. It doesn't really draw 201 W during use.
    Think of it as in your card has 201 W - 145 W = 56 W "OC headroom".

    Yet if you run into issues with SLI, drop overclocks first as they increase power draw especially with overvolting.

    edit 2: missed that vase actually linked a calculation. Pretty much the same result, you can do it but overclocking may be too much.
     
    Last edited: Jun 25, 2016

  11. scipio

    scipio Guest

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    GPU:
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    You're at the limit on that power supply

    Then i read the above post and he summed it up.:eyes:
     
  12. narukun

    narukun Master Guru

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    GPU:
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    Well, it didnt work, as soon as i loaded a scene on Witcher 3 it crashed but works fine on the menu, i tried downclocking without luck, because i just had a chance to play like 5min. and Windows was working fine though, thank you all for the help.
     
    Last edited: Jun 25, 2016
  13. AsiJu

    AsiJu Ancient Guru

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    GPU:
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    ^ that could be due to other things than the PSU. Did you get to try several games?

    Sounds to me like something else was wrong, PSU issues usually cause random instability and the like, not instant crashes when starting a game.
     
  14. narukun

    narukun Master Guru

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    GPU:
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    well what i mean is, when i loaded the game, my savegame is in the most demanded area of Witcher 3, which use like 125~130% of power target, i played a bit there downclocking the GPU but crashed at stock.

    Maybe these cards actually use 201w when 100%
     
  15. AsiJu

    AsiJu Ancient Guru

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    GPU:
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    ah ok, could be the PSU then (or some other thing too).

    Too bad but I understood you weren't going to do SLI permanently anyway?
     

  16. narukun

    narukun Master Guru

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    GPU:
    EVGA GTX 970 1561/7700
    Yes, its my bro 970 i just wanted to try sli because he wont be at home for like a month or so. I don't know what else could be, i already tested both on sli with his machine (he got a 750w seasonic).
     
  17. thatguy91

    thatguy91 Guest

    The PSU would probably suffice, but I wouldn't run even a good PSU near its capacity. At least a 20 percent headroom on maximum load is probably an ideal amount, assuming that you aren't going to add too much later. If you computer requires say 500 W with everything maxed out including overclocking, a 600-650 W PSU would be advisable.

    Remember you have capacity ageing etc to consider.
     

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