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Motherboards Asus Rampage IV Extreme PCI Lane Question

Discussion in 'Hardware' started by Pookeyhead, 17 Jan 2012.

  1. Pookeyhead

    Pookeyhead It's big, and it's clever.

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    I currently have a Asus ROG Rampage IV Extreme board, and have three GPUs in it. I have 2x 580s in SLI driving my main 30" screen and a little GT430 driving my secondary screen.

    The board allows me to have the 2x 580s running in 16X full PCI-E bandwidth, and the second screens card (GT430) running at 8x.. The configuration is like below... (I love UEFI BIOS screenshot facility) :)

    [​IMG]

    What I would like to do is add a 1x PCI device.. specifically a soundcard to the x1 PCI-E slot, and according to the PCI-E simulator in my BIOS that will still allow my 16x-8x-16x GPU configuration.. like this...

    [​IMG]


    However.... I can't get to my x1 slot because it's obscured by my top GTX580... so I thought.. no issue.. I'll stick it in the bottom 8x slot, but the simulator then shows this...

    [​IMG]


    My question is... does the simulator show this because it assumed I'm sticking a GPU in there? You can't specify in the simulator.. you set either occupied, or not occupied. If I was to stick a 1x card in this bottom 8x slot would it cause the GPUs to still be 16x-8x-8x like above, or will only being a 1x card still allow 16x-8x-16x? Does it have to be specifically the 1x slot?
     
  2. logicmike

    logicmike What's a Dremel?

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    I would have thought it would have to be 1x as when you put it in the lower 8x it then is trying to power four cards at the higher rate which is why its lowering one off your 16x down to 8x. is there no way you can get an adaptor, like a 90 degree connector to allow you to still use the 1x port
     
  3. play_boy_2000

    play_boy_2000 It was funny when I was 12

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    The board is hardwired that way; the PCIe 1x is off the x79 chipset, while all the other PCIe lanes are directly from the CPU. PCIe lanes come in 1x 4x 8x and 16x groups, and the only way to split them, is in half (or quarters, below 4x).
     
  4. PhoenixTank

    PhoenixTank From The Ashes

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    I can't answer your question directly... but dropping to x8 on all three isn't actually a problem, if that is what you are wondering. The effect on real world performance is insignificant.
     
  5. Guest-44432

    Guest-44432 Guest

    This was a problem I was facing. I would buy my water blocks for your GTX580's and this would allow you to add the Soundcard to the PCIe x1 slot.
    The problem you are seeing, is the 5x 8/16x PCIe slots are linked to the chipset Which has 40 lanes.
    The 1 xPCIe slot is connected to the CPU's dedicated 8 lanes. Which is why you are seeing the effects.:)
     
  6. Pookeyhead

    Pookeyhead It's big, and it's clever.

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    true_gamer and I have already done tests regarding this in this thread. There is a perceivable difference when dropping one of the cards to 8x. It may have only been single figure fps difference but the thought of doing something the reduce performance, no matter how small pains me :)

    I thought this was the case. I just wanted to confirm it. I'll just wait until I water cool the GPUs as they will, as you say, clear the space needed to get back at the 1x slot.

    I would buy your blocks, but I''d rather wait until Kepler is launched, upgrade them both, and then water cool.

    Thanks for the replies.
     

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