Asus ESC500 G2 - Manual (Page 36)

Chapter 2: Hardware setup 2-18
Use either the 15-pin SATA power connector OR the legacy 4-pin power
connector. DO NOT use both to prevent damage to components and to keep
the system from becoming unstable.
5. Connect a 7-pin SATA cable (from
the motherboard SATA port) and a
15-pin power plug (from the power
supply unit) to the back connectors
of the hard disk drive.
6. Reinstall the front panel cover and
side covers when done.