The only hint I could find in your mobo manual is on Page 41 - Standard CMOS Features. The manual says there are 6 SATA ports in total (so howcum you already have 9 drives?) and the last of these is the eSATA port on the back. In the screenshot on p. 41, I suspect that means the one called "IDE Channel 3 Master" is the eSATA port really. The instructions say you can configure this port to either "Auto" (detect device during POST) or "None" (Ignore this port). So, is your set to Auto? Is your external drive connected and powered on when you boot, so it can be detected?