|If the computer came with ONLY an 80GB hard drive then you may not be able to run a 500GB. |
Watch the POST screens at start up to verify that the BIOS is properly identifying the drive by both the model and the FULL drive capacity.
If you don't SEE any POST screens then boot into the BIOS (setup0 and disable fast boot and any logos. If that doesn't work then try hitting the esc key at the start up to see the POST screens.
If the BIOS only sees about 127GB then your BIOS is NOT 48 bit LBA compliant. You will need to install a PCI based controller card.