Dell Optiplex gx240 Cannot boot from any device.

I have a Dell Optiplex gx240 Cannot boot from any device be it cdrom or hard disk.
It cannot even save the boot device priority, on that window it just displays “n” on devices detected. (I have attached the links to the pictures)
http://pop3.im/gx2401.JPG

Even after Pressing Ctrl+Alt+F8 to select the device manually, it still reports “No boot device detected press F1 to retry or F2 to enter setup.”

It seems the Computer can detect the Drives too well
http://pop3.im/gx2402.JPG