: VIA VT6307 controller providing FireWire 400 connectivity. Front Panel Header Pinout
Using an SATA III (6Gb/s) drive without setting SATA to IDE compatibility. Fix: Enter BIOS > Integrated Peripherals > Onboard SATA Mode > Set to IDE (or Legacy). SATA III drives are backward compatible, but the BIOS must use slower signaling.
Technical details and basic guides can be found on community archives like The Retro Web - ECS RC415T-AM .