Also make sure u have enough space in your PC and your motherboard support PCIe gen 3.0 read the device manual of your PC if u bought it from a OEM company. So before installing a video card in OEM machines like HP that came with windows 8, u must do this process and then boot up your computer and uninstall all the graphic drivers that is installed for your old card in your computer and then remove the old card and put the new one in whether its the nvidia gtx 970 or any card. Also I bought a crosair cx 600 so the graphic card and the rest of the parts has sufficient power to be able to be used. I did this process because I wanted to upgrade my graphic card from a Nvidia geforce gt 620 1gb (came with the PC) to nvidia gtx 970. But I did this process after I updated to windows 8.1, but it doesn have to be windows 8.1 for this process to work. I did this process in my HP envy h8 1437c desktop computer that came with windows 8 preinstalled. For more details about this process, just go to the following link:
This process is usually for a lot of OEM windows 8 machines like HP computers. This a video to show how to disable secure boot and enable legacy mode.