Amigaharry2 - it's a PowerMac G5. The HDD does not spin down. I can see the contents of the HDD just fine from within OperFirmware, the boot command actually loads the boot image from the SATA disk itself but it will either start without seeing anything SATA or just crash if I use any other command line. It's a bug, not a feature :)

Have not tried another HDD, those are original Apple-branded ones with their firmware.