Your post caught my eye(s) since I am a big fan of EPoX motherboards. In fact, I am the proud owner I believe to be the best DF4-SLi motherboard and I also own the Asus and DFI Expert.
You have to use a jumper and set your SATA HD to 1.5G instead of the default 3.0G. I just hope you have such a jumper and the diagram is on the HD label on which pins to short. Good luck.