In BIOS boot flag is on WIndows partition or Windows boot partition with boot files.
But with UEFI the boot flag is used to tell UEFI that the ESP - efi system partition is where to find efi boot files. You can only have one ESP per device.
Remove boot flag from sda4, then UEFI boot may work.
It looks like you left Windows with fast boot or its always on hibernation on. It must be off.
Fast Startup off/hibernation
http://www.eightforums.com/tutorials...ndows-8-a.html
http://www.kapilarya.com/how-to-enab...p-in-windows-8
Many with Gigabyte have issues with IOMMU.
GIGABYTE GA-970A-DS3 motherboard not working with 64 bit kernel - IOMMU
http://ubuntuforums.org/showthread.php?t=2111223&page=5
[SOLVED] GA-970A-DS3P revision 1 no usb 3.0
http://ubuntuforums.org/showthread.php?t=2188370
Make sure you have the latest UEFI update from Gigabyte.
Usually best to have secure boot off in UEFI, but UEFI on or CSM/BIOS/Legacy off.
You may need to add Windows entry back into your UEFI: your ESP is sda2, so you need the added entry:
New Windows entry - assumes default sda1, add -p 2 if sda2:
sudo efibootmgr -c -L "Windows Boot Manager" -l "\EFI\Microsoft\Boot\bootmgfw.efi"
More details on efibootmgr settings & parameters:
http://linux.dell.com/cgi-bin/gitweb...README;hb=HEAD
Still not showing 3rd drive with Ubuntu install?
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