I have an ATI PCI card in my current PC that has a connector on it. The connector was for an ATI ISA TV tuner card. The TV tuner card drew power from the ISA slot but was connected by a cable (like a floppydisk cable) to the PCI graphics card.
It was a pretty cool combo; your TV ariel went in the TV card and you could have TV in a window, or as the windows backdrop even.
The PCI card is branded xpert@play, and was basically a rage pro chip, (or was it rage IIc ?)which has the mach64 core.
I later had an ATI Rage 128, which did better 3D but had a similar clockport-like connector on it; ATI had to send me a new cable with some pins crossed over in order to use it with their TV tuner. I dont have that card anymore. I may still have the ISA TV tuner and cables somewhere though.
ATI ages ago phased out the separate TV card in favour of the "all in wonder" which was everything on one card.
Might be worth looking into.