I just got my sabertooth in today and I'm already having issues. The CPU and VGA lights are on when I power up, and my case fan and cpu cooler don't come on either. I've never installed a new motherboard before. Also, I just now realized that there is no plug for the ribbon cable for my DVD drives. I'm upgrading from an asus p6t deluxe V2. Any advice is appreciated, I don't know why the vga and cpu led's are on. Both my cpu and gpu worked fine on the other mobo.
ribbon cables.... as in ide? make sure you have the power/hdd/etc pins installed correctly, double check your cpu power and any pcie power/ extra power inputs are connected. Reseat the cpu and HSF. Do a cmos clear. Troubleshoot, troubleshoot...
Is your power supply sufficient (you didn't post much about the hardware)?