VGA is analog signal, there's one type of it. I don't understand how there could be different versions of a DVI to VGA adapter, but there are.
For example Matrox Triplehead2Go Digital has 3 DVI-I (both analog and digital) output ports. I want to connect to my projectors via VGA, so I need a DVI to VGA adapter. I'd assume there would be 1 type of DVI to VGA adapter, but there are two types I've found is sold. The manual only mentions you need a "DVI to HD-15 adapter" ( http://www.matrox.com/graphics/media/pdf/products/gxm/en_triplehead2go_guide.pdf ,page 10 )
Here are the two types:
There are a lot of these on eBay and in local stores. Notice there are no pins on the top and bottom of the lone "horizontal line pin" (the C1, C2, C3, C4 pins are missing). I think they are needed to pass analog signal. So what are these adapters? Do some weird devices use VGA ports to accept digital signal? Is that the explanation?
The second type looks like this:
Notice that all the pins are there, including the C pins.
Er, what's the difference? If it weren't the necessary analog pins missing on the first I'd assume it's for single link or dual link DVI, but that's not it...
I'd assume it's for single link DVI, but again, VGA is analog and the C pins are missing too...