Check to see if the GTX750Ti card you purchased uses a UEFI bios. I discovered this caused a conflict at boot with the Gigabyte GA-Z77-DS3H UEFI bios and an EVGA 750Ti card. If this is the case, you may have to try flashing your motherboard bios to a newer version. You might also check to see if your onboard video was enabled. If that was the case, you case use it to enter bios and change to PCIE card and then reboot and hook your monitor to the new card.