Videocon TV shows not supported when connecting computer with HDMI

Hey guys,

I just bought a new Videocon 40 inch LED (VKC40FH) and tried connecting my computer to it using an HDMI cable. But once it boots up, after the BIOS screen and windows logo, the screen goes blank and shows 'not supported'. It works fine if I connect it to my old Samsung TV using HDMI. I am using windows 8.1, HDMI connection is on the graphics card (Sapphire HD5670). Any idea what is wrong??
I have tried both the HDMI ports on TV, nothing works. Any help appreciated.

Thanks