Well i took my best shot at Ben brown but my rig has hit a wall at 17,131 for the first time my rig slow down when i started to over clock my video cards faster. I never seen that before on my rig . Not sure if the 750w PS is running out of power to drive the 4 video cards when overclock and the cards see the system short on power pull them self back or it could be with my CPU only able to hit a max over clock of 3.2 ghz there not enought CPU power to drive the 4 video cards faster . You guys got any ideas ???