5970 and 5870 PSU

I am currently running a 4870x2 in an i7 system, and i know that i can chuck another 4870 in with my 700w Seasonic.
Since the 5970 consumes less power than 4870x2, can i assume my power supply can run a 5970 and 5870 in crossfire?

Thanks in advance.
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  1. It would be a logical assumption - but never assume. Use the power calculator. The one I linked below is free but only shows total wattage. The Pro version (linked on that page) shows requirements for each circuit - the 3.3v,5vc, and 12v circuits. I strongly recommend it and the costs range from just $2 for 3 days access to only $10 for lifetime use.

    http://www.extreme.outervision.com/psucalculatorlite.jsp

    It is an excellent tool with which to become familiar.
  2. Thanks but I cant seem to select both 5970 and a 5870. For "Video Type", and with 5970 selected, is it referring to 2 5970s crossfired, or the two 5870 chips in the 5970 crossfired?

    Either way, with 5970 selected and crossfired its 614 wattage. I guess im in the clear?
  3. blu3skys said:
    Thanks but I cant seem to select both 5970 and a 5870. For "Video Type", and with 5970 selected, is it referring to 2 5970s crossfired, or the two 5870 chips in the 5970 crossfired?

    Either way, with 5970 selected and crossfired its 614 wattage. I guess im in the clear?

    I have no special knowlege about the calculator so I really know no more than you. However, I would assume that it assumes, or only allows for, dual matching cards. So selecting "5970" for the card and "Crossfire" for the type calculates requirements for two 5970 cards. Using that would give you a safe top end.

    What you can also do is set the calculator up with a base system and no graphics card and calculate requirements with no card. Then insert one card - say the 5870 and calculate the additional requirements for that card. Then change the card to the other one - say the 5970 - and calculate requirements for it. Then add the 3 numbers together and you have a reasonable approximation. The SLI charts I have seen show that two cards in SLI actually use less total power under load than two times the requirement for one card - or in your case the amounts for each of the cards added together.

    I checked it out on the calculator which seems to agree. I set up a base system with no video card that required 201w. I added one 5870 and it required 306w or 105w more. I changed type to Crossfire and it required 395w, or only 80 watts for the second card. So the additive method above would overestimate requirements for two 5780s by 25w.

    Perhaps a third approximation, which I would guess would come out a little lower than the additive method above for one 5870 and one 5890, and perhaps would be more accurate, would be to calculate separately Crossfire with 5870 and with 5970 and average the two.
  4. This isn't that complicated. An HD5970 uses a good bit less power than an HD4870x2. An HD5870 uses slightly less power than an HD4870. If his psu can handle those other cards it should be fine for the new setup.
  5. blu3skys said:
    I am currently running a 4870x2 in an i7 system, and i know that i can chuck another 4870 in with my 700w Seasonic.
    Since the 5970 consumes less power than 4870x2, can i assume my power supply can run a 5970 and 5870 in crossfire?

    Thanks in advance.


    better go with 1200w or above if you wanna run i7 with 5970 in cf.
  6. 1200W is way too overkill even for 5970 CF.
  7. Keep in mind that when sizing a PSU, the sweet spot is to have it operating at about 60% of capacity. Above that three bad things start to happen at an accelerating rate. One, the efficiency starts dropping, and lower efficiency, in addition to higher electrical bills, means more heat. Two, the PSU produces a lot more heat, from operating at a higher load plus the reduced efficiency. Three, the fans speed it up considerably trying to expel the additional heat and generate a lot more noise.

    Here is a table reflecting this for a SeaSonic M12-700 700w PSU (I don't know which one you have:

    Power level (watts)..... 300.......400.....500.....600.......672
    % of Capacity...............43%......57%....71%....86%......96%
    Efficiency.....................83.6%..82.8%..81.5%..80.1%..77.7%
    Noise - decibels.............25..........35.......42.......46........46

    Source:
    http://www.silentpcreview.com/article676-page5.html
  8. Thanks for the help. And wow quadfire scales horribly.
  9. Is the OP saying he intends to run a single 5970 and a single 5870 in Crossfire together? His wording isn't entirely clear on this.
  10. His 700w should be enough but I would still opt for a more powerfull PSU, something in the 850w arena....
  11. Hiya,

    Is there anyway to recover or the webmaster recover a very long detailed message I spent hours doing, it explained the PSU situation and why. Also at the end a step by step method from many reviews on how and why you overclock the HD5970, even explaining to first get a voltage OC program from Online if yours came with none! The voltage was dropped not just the core speed, thats why cards rarely reach even the 850mhz 4800 Effective Ram speed. The voltage program advised I forget which it is but if right is not dangerous. It has only 2 settings the current low and normal speed for the 2 GPUs.

    I was in preview when it all vanished?

    Have a wonderful Holiday! Dane

    PS: I won a cheap ($75 below list vs normal $125 above) I paid and just hope the seller still goes through with it!

    Question: Did anyone get a Diamond Brand?? That's what this one is and early shipped Diamond ones had to be RMA's within a week!

    Thanks, Dane
  12. 850 watts recoomended for 2x5970
  13. Dual 5970's is strickly for e-peen purposes....
  14. hell_storm2004 said:
    1200W is way too overkill even for 5970 CF.


    but with core i7...it does necessary...
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