You have done a lot of work!
In my last post I asked if the drives spun up when plugged into your PC (not the Asus P10S-I), by which I mean can you feel the discs are spinning in the drive? Even though these drives are actively balanced there must be some slight vibration you can feel when they are spinning, or at least some noise. Usually, even if a drive is not detected by BIOS it will still power up and spin. Well, I'm pretty sure all drives will, although they may shut down after a while if no host is detected.
So try Hot Plugging the drives using a SATA cable while your PC is running, or better yet an eSATA cable, and see if they spin up.
If the drives don't even spin up when plugged in, then I would say it was a WD problem.
If the drives do spin up, then an ASUS problem.
Either way, WD and ASUS should be doing more to help. Or if you bought from a local store, take the drives back and ask them to test if the drives are detected in one of their systems.