Re: Ubuntu Installation 4 system partitions already on machine
The four partition limit is for MBR formatted disks; yours is GPT.
Your PC uses the new UEFI BIOS -- something I stay away from, so any instructions you follow need to be SPECIFICALLY for UEFI BIOS machines. IF you follow the wrong instructions, you risk trashing the PC. My advise is to wait for "oldfred" to respond -- he seems to know a lot about UEFI and dual-booting.
I would do TWO things BEFORE you attempt the install:
1) Create Win8 Repair CD -- do that using the Backup feature. This will give you a way to recover your Win8 boot loader, should you need to.
2) Install the FREE version of Macrium Reflect and use that to do a backup of the Win8 setup to an external drive.
THEN, if you still want to dual boot, use ONLY the Win8 Disk Management utility to shrink Win8 to make room for Ubuntu. Do NOT use the Ubuntu installer or GParted to do that -- using those risks corrupting the Win8 OS and rendering it unbootable.
Ubuntu 14.04, Mint 17; MS Win 8.1.
Will not respond to PM requests for support -- use the forums.