The SATA ports on 915M08G8KS are in IDE emulation mode. Solution: Enter BIOS > Integrated Peripherals > Onboard SATA Mode > Set to IDE (not RAID or AHCI). Windows XP/Vista/7 will not boot from AHCI mode on this chipset.
The LGA775 socket on this board utilizes an older Voltage Regulator Module (VRM) design. acer socket lga775 pcie motherboard 915m08g8ks manual