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will my psu handle an upgrade to crossfire?

Discussion in 'General Hardware' started by Hybrid_theory, Nov 18, 2012.

  1. Hybrid_theory

    Hybrid_theory New Member

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    Im considering of getting a 2nd 7970, as I ordered two 24' monitors for some triple screen gaming. pCARS is the main reason for that, which i should get around 30fps. But if i decide I want higher fps, not sure if my PSU will handle the load of the two graphics cards.

    I ran fur mark the other day and my UPS reported a load of 400w. In compared to 200w when I was just playing diablo 3, and had a bluray playing on my other screen.

    I looked at benches for the 7970 in crossfire, and the consumption under furmark was about 640w. With my 750w PSU, im un certain if that will do it. Just wanted some opinions.
  2. de.das.dude

    de.das.dude Pro Indian Modder

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    hm... it should run. the max power draw for 7970s are 250W. so two would mean 500W or less.
    add to that 125W for your overclocked cpu and you still have some power left. so i think it should run.
  3. lilhasselhoffer

    lilhasselhoffer

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    Pushing it close, but within reason.

    500 W - Crossfire GPUs
    40 W - 2 HDDs
    40 W - Fans and coolers
    125 W - Mobo+CPU
    705 W


    It's close, but within reason. Most of the time the GPUs/CPU will be closer to idle, so the only time you should be worried is intense gaming.
  4. drdeathx

    drdeathx

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    The answer is yes and no. If your overclocking, no. I just ran how many watts on a killowatt load meter with a 3770K overclocked to 4.7GHz and 2 x Radeon 7970's at 1200/1600 @1.2V and the reading was 775 watts gaming. If your not overclocking you will be relatively safe but I never like pushing PSU's over 90% to tell you the truth.
  5. drdeathx

    drdeathx

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    Your way off on your estimate. Way off.
  6. Frick

    Frick Fishfaced Nincompoop

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    Nah it's pretty correct.

    I would get a bigger PSU to be honest. I'm usually very conservative when it comes to PSU but in this case I'd get a new one. Especially if you're into overclocking.

    Those 250Ws are during Furmark though.
  7. Crap Daddy

    Crap Daddy

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    At stock 2 x 7970 should work with that PSU under gaming load. If you plan to overclock (it is not a necessity since you will already have a a very powerful setup) then there might be a problem. Here's a power draw test with one card:

    [​IMG]
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  8. drdeathx

    drdeathx

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    I ran the power draw myself. Overclocked is much higher. 4.7GHz on a 3770K with 2 x Radeon 7970's @1200/1600(1.2 volts) draw max 775 watts. I don't know how else to explain it but I am overclocked on CPU too. Your chart is probably accurate with 1 card overclocked.

    No its not. I have the raw numbers. Furmark is weaK as Caldave responded in an earlier thread so I ran the draw test myself.
    Last edited: Nov 18, 2012
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  9. de.das.dude

    de.das.dude Pro Indian Modder

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    you are running those cards overclocked. he does not overclock his card. neither did he mention that they are GHz editions!

    as i said, he will just about make it.
  10. drdeathx

    drdeathx

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    You are correct about my cards are overclocked...... and if he does not overclock he is good 2 go but I just happened to run the draw from another thread so i thought I would post the results for him.
  11. Frag Maniac

    Frag Maniac

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    Should be easily enough. 500w/30A for one 7970, and from what I've read the rec for two GPUs is 1.5 times the single rec, which is 750w/45A. That PSU puts out 60A.
  12. Aquinus

    Aquinus Resident Wat-man

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    I don't have a 7970 but those numbers seem kind of high. 700-watts sounds like a max power draw under unusual circumstances. I have an i7 3820 (no stranger to eating electricity,) and two 6870s. Everything fully overclocked won't draw more than 500-watts off the wall (my UPS too has a kill-a-watt built in.) So I find it hard to believe that this will draw as much as you claim it to be unless IVB isn't as efficient as it has been claimed to be.

    With all of this said: Even if I think that the two 7970s do run, you might be pushing your PSU kind of hard which will make temperatures go up, reliability go down, and it will reduce the life of your PSU as opposed to putting less load on it. You can't be too careful with PSUs because a bad PSUs can over volt your hardware if it can't draw enough current which could fry a lot of things on your motherboard.

    The decision is up to you, but I personally wouldn't take the risk and I would get something a little bigger.
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  13. Bo$$

    Bo$$ Lab Extraordinaire

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    you are fine
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  14. Hybrid_theory

    Hybrid_theory New Member

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    It is standard clock speed in the video card. Typically in the past I didn't OC the video card, as it was usually a 1-2fps gain.

    Seems the consensus is that Ill be fine. But with black friday coming up, ill look around for some deals for a new one.

    Thanks all.
  15. Hybrid_theory

    Hybrid_theory New Member

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  16. BlackOmega

    BlackOmega

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    Should be just fine. 7970's do seem to draw a lot of power, however, if you don't OC your cards you'll be fine. Also, keep in mind that furmark is not indicative of a typical load.

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