DVI vs D-Sub

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rhiridflaidd

Weaksauce
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Aug 30, 2006
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Many cheap monitors come with D-sub (VGA) connectors only.

Some of them actually look quite good! So how superior is DVI in reality? For gaming, input lag is a key issue - and has anybody done input laganalyses on monitros that have both DVI and VGA to see which is quicker?
 
Not sure about CRT's, but it's very apparent on an LCD.

My LCD monitor has inputs for both DVI and D-Sub and switch between them often. My main rig for the DVI, and the netbook on the VGA. VGA has a very slight shadow immediately to the right of a pixel. So if you look at the addressbar at the top of your browser, you will notice a gray shadow immediately to the right of each pixel in your text. This 'shadow' does not appear in DVI.

Also when you have a mess of cables at the back of your rig, VGA is prone to interference and you get a horizontal line moving up across your screen, particularly when you start going into the high resolutions. Again, this does not show in DVI.
 
Like you said, some do very well with VGA but other's don't. My NEC 20WMGX2 doesn't like VGA too much, text looks too sharp/contrasted @ native, and anything but native looks like crud compared to same res on DVI. It's a tough call saying you'd be happy with VGA, I can't say I would be, not with the few LCDs I've had. Seems though the older LCDs at my work, 17-19" 4:3 screens do just fine with VGA.
 
If your LCD has both DVI and VGA chances are that the VGA input is quite cheap.
On some monitors there is no visible difference between DVI and VGA (my experience), but on others the difference can be huge.

On monitors only having VGA they are doing it properly since it's the only way to get an image at all. Saying that VGA is inferior just because the VGA input on many monitors are inferior is quite misleading, it's not a proper way to compare the two.

At least for resolutions under 1080p I'd say that there is no difference between DVI and VGA under the absolute majority of conditions. However with VGA you might need some extra tuning in the OSD.
 
It depends on the used RAMDAC, cable and implementation at the display's side. Even DVI isn't immune to a crappy implementation.

A good VGA and DVI implementation will be virtually indistinguishable even at high resolutions.
 
Elledan said:
A good VGA and DVI implementation will be virtually indistinguishable even at high resolutions.
Click to expand...

I agree. My older LCD that has both DVI and VGA I really can't tell the difference between the two inputs, they both look awesome. My mate's monitor that currently resides in my house looks noticably worse on VGA compared to DVI, but that said the whole monitor looks worse. :p
 
I had to switch over to VGA only after the DVI input on my Soyo died. I couldn't tell the difference personally. Using the DVI-->VGA adapter for my video card is kind of annoying though (its a tight fit on the back of my PC).
 
DVI looks better to me. It's a digital connection.
D-Sub is an analog connection.
That's the main difference.
Oh and DVI connectors can be HDCP compliant, so you can play the latest DVDs and protected content through them.
 
vjcsmoke said:
DVI looks better to me. It's a digital connection.
D-Sub is an analog connection.
That's the main difference.
Oh and DVI connectors can be HDCP compliant, so you can play the latest DVDs and protected content through them.
Click to expand...

I only play videos which do not require HDCP, thank you very much. Plus there is nothing fundamentally wrong with analogue. In fact, analogue connections can offer more detail which would be lost with a digital connection (depending on the compression used). Compare recording an analogue sound wave directly (e.g. vinyl) versus running it through an ADC which chops it into pieces and only records some parts of it, to later have it reassembled using a bit of math. Yes, Nyquist and all that.
 
Elledan said:
analogue connections can offer more detail which would be lost with a digital connection (depending on the compression used).
Click to expand...

Not on an LCD. One way or another, somewhere along the line, it is going through an ADC if you're going to put it on a digital display.
 
Elledan said:
Plus there is nothing fundamentally wrong with analogue. In fact, analogue connections can offer more detail which would be lost with a digital connection (depending on the compression used). Compare recording an analogue sound wave directly (e.g. vinyl) versus running it through an ADC which chops it into pieces and only records some parts of it, to later have it reassembled using a bit of math. Yes, Nyquist and all that.
Click to expand...
  1. Video signals originate in digital form (from the frame buffer in your graphics card), and they are consumed in digital form (color values to individual pixels on the panel). There is no such thing as "more detail". Digital links are designed to transmit digital data perfectly; analog links are not.
  2. Nyquist does not apply here because both ends of the link operate on the same frequency; anything above the threshold is noise.
  3. Digital video signals through DVI and HDMI are not compressed.
  4. Vinyl sounds awful because it has terrible frequency-response properties.
 
Re: #1, there is such a thing as an analog video source. Rarely enough so in computing that one wonders that he brought it up at all, but it can happen.

Re: #2 and 3, I'm with you.

Re: #4, you may be technically correct, but your conclusions are something I cannot agree with. CDs can also sound awful, but it is the result of bad data or bad mastering. If your vinyl sounds awful, you're using bad pressings or bad equipment. The character and limitations are different, but it is not implicitly awful.
 
So you need high quality VGA inputs to get a clear VGA signal. On the other hand DVI will show pure clarity even with a cheap monitor.
 
Sly said:
So you need high quality VGA inputs to get a clear VGA signal. On the other hand DVI will show pure clarity even with a cheap monitor.
Click to expand...

Well, the cheapest monitors often only have VGA - and they do fine :) It's when they have both that you should keep that in mind.

The only reason for why VGA is on the cheapest monitors that I'm aware of is that EU has/had(?) a ridiculous tax on displays with digital inputs. I don't know if that has affected other parts of the world but at least before it wasn't uncommon that EU got a special version without the DVI input.
 
chklin said:
  1. Video signals originate in digital form (from the frame buffer in your graphics card), and they are consumed in digital form (color values to individual pixels on the panel). There is no such thing as "more detail". Digital links are designed to transmit digital data perfectly; analog links are not.
  2. Nyquist does not apply here because both ends of the link operate on the same frequency; anything above the threshold is noise.
  3. Digital video signals through DVI and HDMI are not compressed.
  4. Vinyl sounds awful because it has terrible frequency-response properties.
Click to expand...

ashmedai said:
Re: #1, there is such a thing as an analog video source. Rarely enough so in computing that one wonders that he brought it up at all, but it can happen.

Re: #2 and 3, I'm with you.

Re: #4, you may be technically correct, but your conclusions are something I cannot agree with. CDs can also sound awful, but it is the result of bad data or bad mastering. If your vinyl sounds awful, you're using bad pressings or bad equipment. The character and limitations are different, but it is not implicitly awful.
Click to expand...

#1. I was talking about how VGA links have no definite limit to their max resolution, whereas for digital links (DVI, HDMI, DL) there is a set limit.

#2. I used Nyquist as I was describing an example of recording a signal in an analogue vs digital version.

#3. Usually there's no compression, true, but I'm fairly sure it would be possible. One can already send compressed audio (Dolby, etc.) across digital links this way to receivers and such.

#4. As ashmedai said, vinyl doesn't have to sound bad. Most CDs released these days are so poorly mastered even a monkey could do it (slamming open each channel on the equalizer). With proper pressing techniques (vinyl and CD) and proper mastering (actually allowing for soft and loud parts), there won't be a big difference between both media.

Sly said:
So you need high quality VGA inputs to get a clear VGA signal. On the other hand DVI will show pure clarity even with a cheap monitor.
Click to expand...

Even a digital circuit can be messed up to the point where it nukes any incoming signal. In engineering there are few absolutes.
 
ashmedai said:
Re: #4, you may be technically correct, but your conclusions are something I cannot agree with. CDs can also sound awful, but it is the result of bad data or bad mastering. If your vinyl sounds awful, you're using bad pressings or bad equipment. The character and limitations are different, but it is not implicitly awful.
Click to expand...
I know, I know... I was just poking fun at Elledan :D
 
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