GA-EP45-DS3L MoBo - installing 2nd SATA HDD, BIOS won't detect

Hello,

I've tried searching this forum and elsewhere for solution to this problem, but to no avail, so I decided to put this out directly.

A couple of days ago, I bought a new SATAII HDD (WD Caviar Black 750GB) from Newegg to add to an existing, working PC. Here are the specs for the PC:

MoBo: Gigabyte GA-EP45-DS3L with BIOS F10 (latest available)
HDD: WD Caviar Blue SATAII 640GB (SATA port 0)
Two DVD drives - Samsung and LiteOn (SATA, both work fine, ports 3 and 4)
2x2GB RAM
Intel Q6600 processor
600W power supply
Running Windows Vista Home Premium

Everything on this PC works fine (well, as fine as can be), but when I tried installing the new HDD, the BIOS would never detect it. As far as I can tell, it powers up fine when the PC is turned on ('feels' like it is spinning - can't really hear anything over everything else in the case). I tried two different SATAII cables, with no effect. I attempted to connect on all the open SATA ports (1, 2 and 5), but no difference there either.

BIOS settings are:
AHCI enabled
Native mode disabled

I tried enabling native mode to see if that would work, but no dice. I also attempted to get a new driver for the Intel SATA AHCI controller, but Windows says it is up-to-date.

Any suggestions at all out there??? Everything I'm finding on the web either points to people working with new builds (not the case here) or trying to implement some kind of RAID configuration (also not the case) - I just want to add a new, secondary HDD with no OS to the existing system.

Any help/suggestions are greatly appreciated!

Tried that already - I'm just returning the drive, looks like it is busted.