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Graphics DX11 card current draw?

Discussion in 'Hardware' started by jeff1155, 11 May 2011.

  1. narwen

    narwen narwen

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  2. narwen

    narwen narwen

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    double post sorry
     
  3. Deders

    Deders Modder

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    Aren't the 3rd and 4th 12v rails dedicated to the PCIe connectors?
     
  4. narwen

    narwen narwen

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    no

    12V1 supplies the motherboard only, 12V2 is for the EPS 12V power cables, 12V3 is for the peripherals and 12V4 is for PCI-Express. The motherboard ATX connector doesn't need an entire 20 Amps of 12V1 to satisfy it to be honest, but the split seems logical enough.
     
  5. Deders

    Deders Modder

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    Ah sorry, your last post wasn't there when I posted.

    In that case you could try a molex to PCIE adapter, I doubt the peripherals need anywhere near 20A either, probably less than the MB rail does when you take the PCIE slot into consideration.

    Might be safest to make sure that each molex connected to the adapter is on a different cable running from the PSU.

    I still think there is something wrong somewhere if a single 20A rail can't handle both plugs.
     
    Last edited: 13 May 2011
  6. trig

    trig god's little mistake

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    if that is the case, then the pci-e cables should provide enough power on their own. either the card is crap, which could be...i read several bad reviews about the palit sonic 460's, or the psu is faulty...
     
  7. jeff1155

    jeff1155 What's a Dremel?

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    Thanks for all replies, esp. Trig, and thank you also narwen for actually looking something up at last! I did reply earlier and say that both PCIe connectors are on the same 20A rail, while Palit say 24A is required. This is obviously the problem, no matter that 20A should be enough - Palit say 24A, and the card doesn't work - QED surely?

    Trig - which reviews do you read - I have never found current draw quoted in a review, or on a card vendors site, or even on the manufacturers site. In fact the only place I have seen it is on Palit's email - after I bought the bloody card!

    I also mentioned earlier that Molex, SATA etc were on the 3rd rail, so I'll try a dual Molex to PCIe adaptor and see if this missing 4Aish can't be drawn from that. As previous posters have said, the two sockets might have different draws, is there any way of telling? I also see that the PCIe connector has three 12V and three Com, while Molex plugs have 1 12V, 1 5V and 2 Com - shouldn't it be a triple Molex to PCIe adaptor instead?

    And finally, my main question - is 24A a fairly average current draw for a modern mid range (or even high range!) card, or is the Palit card or the GTX460 in general unusually hungry?
     
  8. Deders

    Deders Modder

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    A single 460 should only draw around 160w max, if Palit have somehow nearly double the power required to run this card, then there is something wrong with their design, which I really doubt as I own 2 of Palit's custom design 9800GTX+'s which are not only more power efficient than the standard design with better components (although not all Palit cards opt for better components), but quieter too.

    24A at 12V is 288W. Only high end models with 2 GPU's on the same card draw anything like this amount. It's also close to the kind of figure you'd need to run an entire PC with a 460.

    The PCIE slot is designed to be able to give 75W, as is each of the 6-Pin connectors, totalling to 225W, which is only 18.75A. Falling quite short of 24A, but still under 20A.

    When you factor in that up to 75W will be drawn via the 24 pin ATX connector through the PCIE slot, this figure drops by about a third. The maximum power that is supposed to be drawn through a 6-pin graphics connector is 75W (this is a requirement for the ATX spec and is reflected in the gauge of the wiring used for those wires, which are usually thicker than most of the rest of the wires coming from the PSU).

    So the most 2 of these connectors should be able to have pass through them is 12.5A between them.

    The figure that Palit is quoting you is probably the total for the entire PC, have a look at these figures and do the math yourself. (W=A*V)

    Worth noting that the Guru 3d tests show that the Palit Sonic edition does draw a little more than the other 460's but it's less than 20W more. These figures are for the total system draw taken from the wall, so the PSU will only be supplying around 85% of that figure to the system.

    85% of 20W is 17W, divide that into 12 and it's only 1.417A more than a standard 460.

    QED?
     
  9. jeff1155

    jeff1155 What's a Dremel?

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    Deders

    I appreciate your efforts in responding but I don't know how much more clearly I can say - Palit have told me it needs 24A, my PSU gives 20A, and the card doesn't work. This might not work out with the theoretical design loads of the PCIe connectors but this is what Palit are telling me. I can't say their card is faulty and get a refund if my PSU can't supply what they tell me it needs.

    Take it up with Palit if you won't believe me!
     
  10. Deders

    Deders Modder

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    Could you paste the relevant section of the email in to here?

    Even if they are quoting that for the figure just for the graphics card, it won't need to be supplied via one rail. Your PSU can provide a total of 52A between the 12V rails (624W/12V=52A), so it has more than double the amount that palit specify. Especially when you take into consideration that up to 75W (6.25A) of that power will be drawn from a different rail, the same one that power your motherboard.
     
  11. jeff1155

    jeff1155 What's a Dremel?

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    Deders

    Before anyone starts - by 12V current rating they obviously mean the 12V PCIe supply, not the whole PSU - they actually went on to say that my PSU would be fine, but they as others are overlooking that both PCIs connectors are on the same 20A rail (12V4) on the DPP 650W, and there are no other PCIe connectors, so my only chance is using a dual Molex to PCIe adaptor off 12V3.

    It just seems so weird, 24A seems too high, but Palit say they need it and the card doesn't work, and you just can't get the current draw info from anywhere except tech support, almost anyone you ask just says '650W should be ample' or something similar, and while there are plenty of 650W PSUs with a single 12V rail pumping out 50-60A, there are plenty with a number of 12V rails that only supply 18A. Maybe the DPP 650W is unusual in having it's only PCIe connectors on the same rail - possibly 3+ years ago when it was designed graphics cards just didn't need that much?
     
  12. murraynt

    murraynt Modder

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    3 years ago cards were more power hungry than they were now. If i were you I would send it back to the hop I got it and get a new one. Something is off for sure.
     
  13. Deders

    Deders Modder

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    It says exactly the same thing on the front of my Palit 9800GTX+ box, I'm looking at it now, 450W and 24A. It means the total available to the system via the 12v rail, otherwise how would I be able to run 2 of these cards on a PSU that provides 54A on the 12vrail? 48A would leave me with 6A which isn't going to be enough to power my CPU, let alone anything else.

    You're also not taking into account that the only 2 thirds of the cards power will be drawn from the 4th rail.

    I agree with Murraynt, I think the card is faulty.
     
  14. jeff1155

    jeff1155 What's a Dremel?

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    Well, since everyone thinks it's weird, I'm querying the 24A with Palit on the basis of 75W per PCIe and 75W from the slot, plus 160/12 = 13.33A, not 24A, so we'll see what they say.

    I'll let you all know!

    Anyone point me to a decent Molex to PCIe adaptor in the meantime?
     
  15. Deders

    Deders Modder

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    Ask them if the 24A figure is for the card itself or the entire system.

    As for molex-PCIE, some come with 5 wires, some with 6, no idea why, the one that came with my Palit card had 5, i needed to buy a second but that had 6. It wouldn't power on with the 6 wire adapter so when I took it back and explained, the guy at the shop just cut the 6th wire. it worked fine after that.
     
  16. trig

    trig god's little mistake

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    if i can find the article, i'll pm you what that's all about...
     
  17. Fizzban

    Fizzban Man of Many Typos

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    So? You are going to need to use 2 cables for the more powerful gpus anyway. Just make sure each cable is on a different rail. For many cards that would be enough.
     
  18. jeff1155

    jeff1155 What's a Dremel?

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    Trig - can you PM it to me as well? The adaptor I've just bought has 5 pins, 2 12V and 3 com, with one of the 12V having two wires from one Molex, and the other just one from the other Molex. Hopefully there's a good reason!
     
  19. Blarte

    Blarte Moderate Modder

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    [​IMG]

    thats my current draw of a DX11 card :naughty:
     
  20. trig

    trig god's little mistake

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    yeah, tru that
     

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