To access the BIOs setup power up your system and press F2 at the Dell BIOs.

You will be taken to the main BIOS tab

Use the → arrow key to move to the advanced tab.

Press the ↓ key to take you down to the System Configuration and Press Enter.

On the advanced tab press the ↓ arrow key to move to SATA Mode. Press Enter to modify the catagory between AHCI and RAID. Use ↓ and ↑ to select your setting and once again press Enter.

Press esc to take you back to the earlier menu and esc again to exit.

Select Yes when prompted to Save Configuration and Exit.