A couple of things to try, you might have but it might be different on the Asus, you have to go into the bios, I think it's integrated peripherals, the 4th one down on the left, then on the list choose the second one down for sata, enable it then highlight where your drives are attached, might as well highlight them all.
Then save and exit, press f10 to enter the menu make sure you choose strip or mirror whatever you need then take both drives from the left pane to the right pane, using the curser, then I think it's f7 then set to boot by pressing B.
Then restart you shouldn't need to press F6 for me it just loads and installs.
I had a similar problem to this and was missing one of the steps I think it was the one in the BIOS integrated jobo.
Hope this sorts it