Thoughts on DVI connections

[AVITRY]

My friend bought a used but very nice 23" LED HP monitor. It was used only a short time, but in that time the original owner lost the DVI cable. He has it connected to his computer via the VGA cable on both video card and monitor.

Both his video card and monitor have DVI connections. He asked me if I thought the picture quality would be noticeably better with the DVI cable, and would buying one be worth it.

Well, I had my doubts that any real noticeable difference would seen, but I don't know .... What do you all think?

thanks,
joe

[RJ Johnston]

I noticed a difference, but I wouldn't say it was a big improvement, just a small improvement. Those DVI cables can get expensive.

[RJ Johnston]

EDIT: I just tried the VGA connection again and tried remembering what I saw when I went back to the DVI connection to compare. I couldn't see any difference when looking at this web page.

[Bob]

He asked me if I thought the picture quality would be noticeably better with the DVI cable, and would buying one be worth it.

I wouldn't worry about it. It's not going to be something that stands out and says "notice me". Unless it's a very high end monitor, it's probably not worth it.

[Chris B]

When I was comparing such things I found DVI cables to be sharper and I never looked back. It's perfectly possible that VGA interfaces have improved. The nice thing about a DVI cable is that a monitor is driven at exactly the right resolution - there's no "auto adjust" or the like - and they're only around $8 (from a quick search).

[AVITRY]

Thanks guys!

[Bob]

There used to be a huge difference. I can still remember vividly how much better the dvi interface was on the first monitor I owned that supported it. Digital to analog converters are a lot better than they used to be and it's possible to get a fairly accurate resampling of the signal. The problem is that the conversion from digital to analog in the video card produces a stepped signal. Ideally, those steps would have steep sides and flat plateaus. In practice, the steps are rounded and the plateau is narrow. Because there is no pixel timing clock in the vga signal, the monitor has to make a best guess as to the position and levels of the plateaus. This is the "auto setup" that Chris mentioned. Most of the time, this works well and an excellant reconstruction of the digital signal is possible. Sometimes it doesn't work well and the result is a fuzzy or jittery image. The analog signal is also subject to interference and ghosting. Especially in long cables. If your friend is not experiencing these problems, the vga cable is probably adequate. If he is experiencing any of these problems, a dvi cable is recommended. He will need to get the right type of dvi cable -- see this: http://www.datapro.net/techinfo/dvi_info.html

My personal preference is to use the dvi cable.

[RJ Johnston]

I decided to record some video of my monitor showing text on this web page in VGA and in DVI mode. My video camera was in 1920x1080p macro mode six inches from the screen. I can now say without a doubt that the DVI is noticeably sharper under those circumstances.