UKickAss :
Hi, I wanted to change my old graphics card to a gtx 750 ti. But, when I start my pc it is stuck in the boot screen. I heard that it might have something to do with secure boot but all the tutorials I havd seen have just been tutorials for windows 8. Please help!
From personal experience, altering any hardware devices may need you to reinstall windows.
I would suggest you made a backup of your current files on an external hardware and then re-install windows.
You can also perform another task which is called "dual-boot". Dual boot let's you select which installed OS you want from, keep in mind they need to be in separate partitions or harddrives.