Windows 8 Option Not In Grub On Ubuntu 14.04
Problem: Windows 8 is not showing up as an option on my Ubuntu 14.04 Grub Menu
Solution: The boot files of [The OS now in use – Ubuntu 14.04.1 LTS] are far from the start of the disk. Your BIOS may not detect them. You may want to retry after creating a /boot partition (EXT4, >200MB, start of the disk).
This can be performed via tools such as gParted. Then select this partition via the [Separate /boot partition:] option of [Boot Repair]. (https://help.ubuntu.com/community/BootPartition)
You can now reboot your computer. Please do not forget to make your BIOS boot on sda (500GB) disk!