DVI-D to VGA cable

Can a DVI-D to VGA cable or DVI-D to VGA adapter be used to connect my PC to plasma screen? From time to time you might be confused by so many buzzwords and new stuff about video and then you have to ask the question like this. You know, you are not the first one who would like to ask such question and definitely not the last one too. Technological innovation is intended to make life easier and richer, and please believe that at most it is just the temporary happy trouble.

Typical questions about DVI-D to VGA cable

These are typical problems you might encounter if you need conversion between two different video signal formats. In such similar situations, what would you do? And can you explain why they did not work?

Example 1 about DVI to VGA

If your video card comes with two ports, one is VGA and the other is DVI-I, while your display has only VGA port, now you would like to hook them up by using a DVI-D to VGA adapter or cable. But no matter how many times you have tried, it just kept failing. However, if you connect them by a DVI-I to VGA cable or DVI-I to VGA adapter, it does work. What is the reason for that? Why it kept failing since DVI-I is compatible with DVI-D?

Example 2 about VGA to DVI-D cable

If your video card comes with only VGA port while monitor has both VGA and DVI-D port, now you connect them with DVI-D to VGA cable and it did not work. What is the reason for that? Are there any other ways to solve it?

Basic knowledge needed to understand DVI to VGA

There are total 5 different types of DVI interface, including DVI-I (dual channel), DVI-I (single channel), DVI-D (dual channel), DVI-D (single channel), and DVI-A.

Single-channel DVI-I connector can be degraded to D-Sub connector by a DVI to VGA adapter, which only extract the analog signal information from DVI-I input to VGA output. However, DVI-D connector is a different story. It is because “D” here is the acronym for Digital, which means it is able to transmit digital data instead of analog signals.

Single-channel DVI-I is “18+5″ pins while single-channel DVI-D is “18+1″ pins. Single-channel DVI-I is compatible with single-channel DVI-D. Dual-channel DVI-I is “24+5″ pins while dual-channel DVI-D is “24+1″ pins. Similarly, dual-channel DVI-I is compatible with dual-channel DVI-D. In other words, a “24+1″ DVI-D display male connector can fit into the “24+5″ DVI-I female connector. That means the other 4 pins for analog signal do not need to work. On the contrary, a “24+5″ DVI-I can not fit into the “24+1″ connector at all.

Answer about DVI to VGA cables

Now since you have the basic knowledge about the conversion about DVI to VGA, probably you can come up with the answers to the above-mentioned questions. So here are the brief replies just for your reference.

Let’s get back to the example 1. The DVI-D to VGA cable doesn’t work because the signal sent from DVI-I to DVI-D is digital only, which is totally incompatible to VGA analog displays. It will be seen from this that a simple DVI-D to VGA cable here doesn’t make any sense except it can convert digital signal to analog signal, which actually can be done with a DVI-D to VGA converter box.

In the example 2, logically here it needs a VGA to DVI-D cable instead of the opposite one. It did not work because the same logic of example 1 except its video card allows the output of a digital signal through the VGA port. Seemingly here you need a VGA to DVI-D converter box instead of a simple DVI-D to VGA cable.