Guaranteed there would be a bottleneck. I had a bottleneck with a 1950pro on that board's younger brother....
Asrock 4CoreDual-VSTA review. (Damn that's a long time ago.... ;) ).
I think the minimum for a recent card would be an 8X, and even with that you'd be facing a possible bottleneck. That said... what are you moving up from? Could be that you'd still see an improvement depending on your current setup, and you could always move up to a better board in the future.
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