crossfire r9 280x PCIe2.0 x16/x16 vs PCIe2.0 x8/x8?

i want to add another r9 280x to my system but my motherboard a Asus M5A99X EVO Rev 2.0 only runs crossfire in x8/x8 would it be worth upgrading my motherboard to a Asus Sabertooth 990FX R2.0 that runs crossfire in x16/x16 would there be that much performance difference between 2 r9 280x crossfire in PCIe2.0 x16/x16 and 2 r9 280x crossfire in PCIe2.0 x8/x8
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  1. bolton1001 said:
    i want to add another r9 280x to my system but my motherboard a Asus M5A99X EVO Rev 2.0 only runs crossfire in x8/x8 would it be worth upgrading my motherboard to a Asus Sabertooth 990FX R2.0 that runs crossfire in x16/x16 would there be that much performance difference between 2 r9 280x crossfire in PCIe2.0 x16/x16 and 2 r9 280x crossfire in PCIe2.0 x8/x8


    You may experience a slight decrease in performance, but I highly doubt it would do much. Great boards, you should see much of a difference. The PCIe2.0 x16 would be optimal.
  2. I think you´re confusing things. Usually mobos have:

    1 PCie 3.0@16x; 1 PCIe 2.0@ 8x(if you Xfire you´ll end up with 8x;4x). SLI is not even an option because the ports are different.

    Or;

    2 PCIe 3.0@16x; 1 PCIe 2.0@8x (if you Xfire/SLI it will divide, meaning you´ll run @ 8x;8x. If you add a 3rd card you´ll end up with 8x;4x;4x

    You won´t notice much difference in FPS numbers but you will surely notice a gameplay smoothness improvement.
  3. Agente Silva said:
    I think you´re confusing things. Usually mobos have:

    1 PCie 3.0@16x; 1 PCIe 2.0@ 8x(if you Xfire you´ll end up with 8x;4x). SLI is not even an option because the ports are different.

    Or;

    2 PCIe 3.0@16x; 1 PCIe 2.0@8x (if you Xfire/SLI it will divide, meaning you´ll run @ 8x;8x. If you add a 3rd card you´ll end up with 8x;4x;4x

    You won´t notice much difference in FPS numbers but you will surely notice a gameplay smoothness improvement.


    His motherboard does not have PCIe 3.0. Running at PCIe 2.0 x8 will not decrease performance by any noticeable amount.
  4. As stated you may see aa few % increase in FPS with x16 x16 but nowhere near enough to justify a new board.
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