I haven't used SATA drives on a PC yet (other than in a USB box), though I have used motherboards which support them. I remember there were certain settings on the BIOS setup which would affect which drives were seen first, SATA or PATA, if both were used.
On this computer you can't change that, as Channel 1, Channel 2, Channel 3, Channel 4 display in that order, with IDE for Channels 1 and 2 and SATA for 3 and 4. You can change the boot order, however. Within the Hard Drive Group, you can select what hard drive you want for the boot drive. Mine is set to the SATA drive on Channel 3.
It may be that other motherboards offer more choices. This one is an ASUS made for Hewlett Packard and the BIOS offers fewer choices than a non-OEM ASUS. However, even if more choices were available, I never changed anything like that. So the mystery remains (creepy theremin music in background