Hidden SATA ports? Need some help with configuring BIOS please

I have a p.c. with a Supermicro X7DWA-N motherboard, which has 6 SATA ports. The p.c. has four SATA II HDDs and one SATA DVD Writer installed. There are two Quad Core processors (E5462 2.80G) fitted

There are no IDE hard drives, floppy drives or CD drives connected.

My operating system is 32-bit XP Pro SP2.

The problem I have is that only the first four SATA ports are recognised by the Phoenix BIOS. I am assuming that ports 5 and 6 are hidden, because they do not appear in the BIOS screen and any SATA device plugged into ports 5 and 6 are not detected by the BIOS or Windows XP.

Please can you tell me how to enable SATA ports 5 and 6?

In the BIOS set up, I have the following settings:
Parallel ATA - Disabled
Serial ATA - Enabled
Native Mode Operation - Serial ATA
SATA Controller Mode Option - Enhanced
Serial ATA RAID - Disabled
SATA AHCI - Disabled

Are these OK for a non-RAID system?

This is a stab in the dark: maybe the extra two are part of the RAID function? Do you have any settings for the SATA RAID other than enable/disable?

^^ good thought, or they are under a different chipset, so diff section ?