Pretty sure it isn't your TV, if it was you wouldn't have an image on your TV that comes from your Computer. If you are seeing the computer screen saver on the TV it is receiving a signal.
If you have multiple places that the HDMI cable can be plugged into your Computer try switching the cable to the other one most video cards have two HDMI ports. Did the images swap on the TV and Monitor? This is a pretty safe test because you can just switch them back if it doesn't display correctly.
Next
Go into Display Settings by right clicking on your desktop.
Have it "Detect" the screens available to use.
Click Identify and see what number your Monitor is.
Scroll down and select "Duplicate these devices".
You should see the same thing on...