Post code d8 indicates a misconfiguration in the bios.  This can happen after changing either the CPU or RAM.  It can also happen if overclock or ram settings are not correct.  This can easily be fixed by clearing the bios.  To clear the bios you will need to remove bios battery and disconnect the power.  Then allow the computer to sit for 10 mins.  Replace the battery and plug in the computer.  Then test again.  If the issue persists please contact technical support. 1-888-880-3824