HDMI connected devices are designed to "handshake" or detect each other but they don't do this all the time so the order that each is turned on matters. If my laptop is booted and I select it I won't get a picture but if I select the input and then boot the laptop is works fine. Try changing the order. You can also try selecting a different active input and then go back to the PC.
Does your PC detect the TV? Set it as your second display and make sure that the resolution is set to the native resolution of the TV.