Windows programs always show the size in HEX GB's of the formatted disk. The drive manufacturers compute the advertized disk size in decimal GB's of the unformatted disk. So you don't have any LOST bytes.
1024 bytes in a kilobyte (KB)
1024 KB in a megabyte (MB)
1024 MB in a gigabyte (GB)
You might try removing the hard disk and starting the computer that way. The F12 option should always allow you to enter the BIOS. There are times when a failed HD will not allow the BIOS to complete the POST hardware checks. It can also happen with failed memory. So you might try to swap out one memory card at a time.