have a P8Z68-V GEN3 mainboard ,
And try to install a graphic card on it .
The graphic card is the radion saphhire RX580
What to do now ?
As mentioned you need to post your computer information including CPU/APU and Windows version and AMD Version installed.
If you have an Intel APU (Processor with Integrated Graphics) make sure you have in BIOS settings on "Auto" when deciding which GPU (integrated or Discrete) will be your Main Display device when booting up. Normally when you install a GPU Card with an APU installed, BIOS automatically switches from Integrated to Discrete GPU Card as the Main Display Device for booting up and using. So you must have your monitor cables connected to the GPU card and not the motherboard to get video.
Make sure you have the GPU Card installed on the first PCIe x16 slot.
Is your GPU card recognized in BIOS?
Make sure you have your monitor connected to the GPU card and not the Motherboard video outputs.
How is your monitor connected to your computer? HDMI, DP, DVI, VGA or with an Adapter?
Does your RX580 show up in Device Manager under "Display"?
Do you have the RX580 Power cables connected from the PSU to the GPU card?
It requires Two PCIe Power cables from the PSU to the GPU RX580.
Do you have your tv connected to the HDMI port on the RX 580?
Is the RX 580 not displaying any image, is the driver you installed not working? State clearly what the problem is!