BIOS Modes

I have an old Intel DP55WG motherboard with Windows 10 Home (64-bit) 
installed.

The board has an LG DVD optical drive and a WD hard drive (500 GB) 
installed.  Both are SATA and connected to separate SATA controllers on 
the motherboard via their cables.

If I go into the BIOS and change the SATA chipset setting to IDE, I am 
able to boot up with the hard drive, but not with the DVD drive.  This 
even though the HD is SATA.

If I change the chipset to AHCI, I can boot up with the DVD drive but 
not with the hard drive.

I thought about flashing the BIOS but Intel no longer offers support for 
such an old board.  The only other repository of BIOS files I could find 
seems to have one that is older than the one currently in use.

If anybody else has run into this issue and was able to solve it, please 
let me know.

Thanks.
-- 
tb