As always, you couldn't be more correct. Now, only one of the two 2TB drives is showing up.
Since my original post, I have conducted the following steps:
(all four drives were showing up on POST at the time)
1. In the BIOS, I setup PCH SATA Control Mode to "RAID(XHD)" per the manual to allow me to configure a RAID.
2. After reboot, all four drives were recognized by the RAID controller and I entered the RAID configuration utility using "CTRL-I".
3. Once in the utility, I noticed both 1TB drives were listed, but only one of the 2TB drives was listed. (even though, it showed up during startup).
4. I went ahead and set up a RAID0 configuration using the two 1TB drives. No problems.
Now, whenever I startup the machine, only one of the 2TB drives shows up.
I love building new machines, but these little things get so frustrating, LOL.
Also, under "Advanced BIOS Features" I set "Delay for HDD" to 5 secs, do you think that is adequate?
standing by for additional help, thanks everyone!