It sounds to me like you have not set up your new drive correctly in the Dell BIOS. Enter the BIOS. On the first page you’ll see a listing of the devices connected to your computer. These are the devices that the BIOS recognizes. Look at the listing for the first hard drive (sometimes called HD 0). If this entry is missing, garbled, or otherwise incorrect, set the BIOS to recognize the drive automatically (AUTO). Save your changes and reboot.