Depending on the games, AMD cards run like crap and could bottleneck your cpu. For example, the R9 290x 4GB gave me lower fps in Pokemon Colosseum compared to my GTX 580 3GB. If you can't get full speed in Pokemon Colosseum then it's an AMD issue. I'm getting beyond full speed in that game.
[color=#3366ff]CPU: Intel Core i7 4790K OC'ed @ 5GHz[/color]
[color=#339933]GPU: MSi N580 Lightning Extreme 3GB[/color]
[color=#cc3333]RAM: CORSAIR Vengeance Pro 16GB DDR3 @ 2666MHz[/color]
[color=#333333]HDD: Samsung 840 Pro SSD 512GB[/color]
[color=#6666ff]CPU cooler: Noctua NH-U14S w/Noctua NF-A15 PWM 140mm Premium[/color]
[color=#ff3333]MOBO: Asus Maximus VI Hero LGA 1150 Z87[/color]
[color=#cc3399]CASE: Thermaltake Urban T81 Full Tower[/color]
[color=#339933]GPU: MSi N580 Lightning Extreme 3GB[/color]
[color=#cc3333]RAM: CORSAIR Vengeance Pro 16GB DDR3 @ 2666MHz[/color]
[color=#333333]HDD: Samsung 840 Pro SSD 512GB[/color]
[color=#6666ff]CPU cooler: Noctua NH-U14S w/Noctua NF-A15 PWM 140mm Premium[/color]
[color=#ff3333]MOBO: Asus Maximus VI Hero LGA 1150 Z87[/color]
[color=#cc3399]CASE: Thermaltake Urban T81 Full Tower[/color]