Most motherboards designed for CrossFire or SLI are going to place the secondary PCI-e x16 slot a few slots down to allow for better airflow. I wouldn't consider your Sabertooth to be an exception or anomaly here. From the looks of the case, the PSU is below the height of the bottom of the motherboard, and the second graphics card will not extend below the bottom of the motherboard. I don't see the graphics card contacting the PSU.
If it's not clear, your second x16 slot should place your graphics card right about where the third one is in the picture I linked to.