Knowing the hardware would help, but first though if Intel, is if you are using a Discrete GPU (a graphics card) have you gone into the BIOS and set primary video to PEG/PCI. Is the video cable attached to the mobo or the GPU itself? Is the TV set to the proper input source? i.e. if using a HDMI input from the computer do you have the proper HDMI input selected for source on the TV