Reducing the resolution (in full screen mode) helps running the game with slower cards though. The required videocard heavily depends on the resolution. When trying to run the game in 3840x2160 resolution two Radeon HD 6970 cards in CrossFire mode were needed to run the game, but when reducing to 1920x1080 a single card could run it at 60fps. At 800x600 resolution the required GPU power will be significantly less (4x less pixels). If the lowest possible resolution still doesn't help, a new card is the only option.