Card is 2GB ATI Radeon HD 5450 . Tv is Samsung 42". I use Windows 8.
I tried doing what FruitBat says but as soon as I connect the cable I get the desktop. Then I right click for screen resolution and I get the Icon in the tool bar (the base of the screen) but it doesn't open. Also it doesn't allow me to open any other program(int exp....etc).
I changed the HDMI cable for a new one. When I right click the screen res. I get just monitor 1. If I click detect I just get another litle box rthat says "Another display not detected" and that's all. Doesn't give me any option. If I disconnect the VGA cable the mitor gets black and I have re-started the pc a few times but does't help.
Jollyjohn has probably got the answer. You will have to change the input setting on the TV. If you had posted the model number then of your TV rather than just make and size we would probably be able to tell you exactly how to change the input so that the TV shows the signal from the HDMI connection.
On my TV remote I have a Source button which enables me to change the input settings. Have a look at your remote for a similar named button and change it to HDMI and you should be able to see your PC.
If the TV is on or in stand by mode it will always send a small current through the HDMI cable to the Computer and will show as a second monitor.
Some TV's will only use one HDMI connection slot for a computer so check your instruction manual.
You could try:
Disconnect monitor. Connect computer to TV via HDMI only. Turn TV on to correct HDMI channel and boot computer. If you are getting a signal from computer to TV before windows boots the problem is likely the drivers.
If you have used the drivers supplied try down loading the latest drivers from the manufacturers web site. Uninstall all drivers and re install.
If it does not show on boot up try re seating the graphics card.
I did what Brynit says but still not luck. The tv/monitor Samsung series 5, I have used it for 2 years. It has 4 HDMI ports. tried all of them. Using the remote control and trying to connect from the options given (tv-monitor-hdmi-etc)and then using a litle red buttom(A) to refresh, it tries to get any "device" connect it but can't find any. Any other suggestion?.