PCIe 16x Video Card Throttled to 4x?

I am building a new computer and I need a motherboard to go with an ATTO ExpressPCI UL5D Low-Profile pcie 4x Raid controller. I've been looking all over the net, but I can't seem to find an answer to this question anywhere. Will there be any performance hit with this card and a pcie 16x video card in the same board? Most new motherboards have multiple pcie slots available. I know if you want to run two video cards, and one is 16x and the other is 8x, then the cards will run at 8x. What will happen with a pcie 4x raid card? Will my video card be throttled to 4x? The Raid card will be only used for a Dell LTO-3 backup drive, and the drive will only run backups after hours.

To give you some background, this will be a non-gaming workstation. I'll need to work with mostly Autodesk software: AutoCAD, Revit (all of them), Civil 3D, and maybe Photoshop and Solidworks. I won't be the tech pumping out the designs, but I may need to play with the models if the users have problems with the software. I'm usually a fan of Gigabyte motherboards, but I'm open to anything.

Oh, and any suggestions for a video card would be greatly appreciated. In a perfect world I'd get an expensive Quadro card, but I'm trying to keep my video card in the $200-$250 range. Maybe a Quadro fx 580? I could probably get away with a GeForce GTX 260, since they're around the same price, but I imagine I'll get better performance with a workstation card for what I'll be doing.

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  1. Dang. Looks like my first post is a major bust.

    Sorry guys. Was it that dumb of a question?

  2. Best answer
    the slots should auto negotiate to x8/x8 and the raid card can only use x4, now any video card you have should be running at x8 since thats the number of lanes the the motherboard will give it (with cards in both slots)

    now if the slots are PCI-E 2.0 x8 you shouldn't see a bottleneck (it's about 4% with the fastest single gpu cards like the 5870 and GTX480)

    as for Quadro vs GeForce, i don't know the apps and whether they would benefit from the Quadro or not (not really a GPU workstation guy), but a GeForce card in the $200-250 range would be the GTX460 which will be quite a bit faster than the GTX260
  3. Awesome! That's exactly what I was looking for. I knew the card would only run at 4x, but I was worried that somehow the pcie lanes would use 4x because of the card. Sorta like when you put two different but compatible sticks of RAM in the same motherboard, they run at the slowest speed.

    It'll definitely be a pcie 2.0 motherboard. I just don't know which one I'm going to get.

    It seems that the newer versions of the Acad software rely on DirectX and D3D, and not OpenGL. I'm not sure how optimized the DirectX drivers are for Quadro cards and Autodesk software. I could probably get away with something like a GTX460. I'll have to shop around.

    Thanks mindless728!
  4. Best answer selected by jterschak.
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