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

Last response: in Graphics & Displays
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July 3, 2014 12:29:00 PM

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
a b Ĉ ASUS
a b V Motherboard
July 3, 2014 12:31:44 PM

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.
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July 7, 2014 5:19:23 AM

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.
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July 7, 2014 5:27:21 AM

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.
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a b V Motherboard
July 7, 2014 7:34:48 AM

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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