I tried to connect my PC with my Toshiba LCD TV using an HDMI cable.
PC did not detect my TV; however everything works fine with VGA cable.
HDMI cable is not defective since it works perfectly fine between PS3 and the same Toshiba TV.
ASUS M4A88T-M AMD 880G Socket AM3 Motherboard
AMD Phenom II X2 550 3.1Ghz Black Edition AM3 CPU
RAM 8 GB
Windows 7 - 64 Bit
You may have to access Catalyst Control Panel's "My Digital Flat-Panels" section and setup the HDTV format support.
Have you tried booting the PC while only the TV is connected via HDMI, or are you attempting to switch while the PC is already started? Some GPUs don't like to switch to a newly connected display while a different one is active, especially when the active one is connected to the (analog) VGA output, and the additional one is being connected to a DVI or HDMI (digital) output. It is also entirely possible that the VGA and HDMI output are actually on a shared display output channel, in which case only one can be operational at a time.