Who is the manufacturer of the GPU Card? Also do you have the 6 pin GPU Power cable connected from the PSU to the GPU Card?
The GPU Card doesn't show up in BIOS nor in Windows Device Manager?
You didn't indicate which Windows version you have installed?
If the card is properly connected and it works on another computer it could indicate either a bad Motherboard PCIe slot or possibly a defective PSU.
Make sure you have the GPU installed on the correct PCIe x 16 slot and not on the PCIe x 16 x4 slot. Also make sure you have BIOS configured to have the GPU Card as the main Graphic Display and not the Intel Integrated Graphics.
Make sure you have the latest NON-BETA BIOS installed "F13". There are two other newer BETA BIOSes to install or try: GA-Z77M-D3H (rev. 1.0) | Motherboard - GIGABYTE Global
Also see if there are any newer Intel Chipset and Integrated Graphics drivers for your motherboard. Most are from 2013. Download and run Intel Driver and Support Assistant to update all of your Intel Motherboard's drivers to the latest versions.