I have a second drive that was fine until it was moved into a newer machine. The previous board had BIOS and recognized the drive every time, but the new Z77 6 ASROCK with UEFI gets it around one in twenty reboots (if lucky) and lists it as "AHCI P2: __Something__" (Its "ST" something with numbers IIRC).
Can I force it to wait for the drive to start either in this new UEFI or Linux (Xubuntu 12), or if I install Windows on the second drive? Any other ideas? All data seems to be intact when I can get to it last I checked (approx 250 Gb i think).
The STxxxxx is the Seagate drive model. It sounds like you have it on one of the Intel SATA II ports, right?
If you have nothing else on the ASMedia ports, you might try attaching it on one of them and setting the ASMedia controller sata mode to IDE -- it is a separate setting below the Intel sata mode setting on the bios page.