Recently I bought a DVI-I to RGB cable in the hopes of connecting my computer to an old LCD TV that only has a component input avaliable. My computer only has DVI, VGA and HDMI. When I connect them, I get a pink, green, static with wavy lines.
When I have my regular monitor connected (through VGA) to my computer, AND the TV connected to the computer, I attempt to connect to an external display and a similar thing happens. If I choose duplicate, or extend, and select some certain resolutions, I get a pink tinted, looping display on my TV which shows My WALLPAPER but very staticky. It doesn't show my screen, windows, icons and all. This leads me to think that connecting them is possible, I'm just not doing something right.
My graphics card is a NVidia GeForce GT 220. When I try to connect to the TV with the NVidia control panel, (cloning or w/e), it detects the TV but nothing shows up on the TV. Not even that pink static.
Try to find the manual for your TV. It will tell you the resolution and refresh rate that is supported at the component ports. There might also be a settings menu on the TV for this ports. In most cases 640*480/60Hz is a supported resolution.