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DVI vs. VGA


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#1 Daniel0

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Posted 08 October 2006 - 05:50 PM

Would I achieve any visible quality improvement by using a DVI cable instead of the VGA cable I currently have for my monitor?

#2 .josh

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Posted 08 October 2006 - 06:15 PM

sure, if your monitor supports resolution and contrast ratios beyond what a vga cable can handle.
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#3 448191

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Posted 09 October 2006 - 06:32 PM

Correct me if I'm wrong, but I believe the only practical advantage of DVI over VGA is that of eliminating signal loss. If you use a short, high quality VGA cable, nobody will be able to spot the difference. I have had my monitor on both VGA and DVI, and I can't spot the difference. When I tried an old VGA cable, I did spot some minor differences though.

#4 ober

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Posted 09 October 2006 - 07:17 PM

That was my impression as well.  VGA cables can introduce things like ghosting, but often you only see it on poor quality VGA cables or when the cable is more than 20 feet.

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#5 .josh

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Posted 09 October 2006 - 08:04 PM

a dvi is a digital connection.  a vga is an analog connection.  with a digital connection, the signal is either on or off, no in-between.  with vga, you can get partial/fuzzy signals (what you would get if you use the poor quality vga cables that you mentioned, for instance). 

when you have a vga cable, the signal going from your computer to your monitor is converted from a digital signal to an analog signal. this creates a small amount of signal loss.  if you have a digital monitor, and you are using a vga connection, you are getting twice the signal loss, because the computer has to convert the signal from digital to analog, then your monitor converts it back to digital when it receives the signal. 

also, dvi can xfer/process larger amounts of data at higher speeds than vga.  this means better graphic output capabilities like faster framerates with better resolutions.
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#6 448191

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Posted 09 October 2006 - 08:29 PM

a dvi is a digital connection.  a vga is an analog connection.  with a digital connection, the signal is either on or off, no in-between.  with vga, you can get partial/fuzzy signals (what you would get if you use the poor quality vga cables that you mentioned, for instance). 

when you have a vga cable, the signal going from your computer to your monitor is converted from a digital signal to an analog signal. this creates a small amount of signal loss.  if you have a digital monitor, and you are using a vga connection, you are getting twice the signal loss, because the computer has to convert the signal from digital to analog, then your monitor converts it back to digital when it receives the signal. 


Which is exactly what I implied by saying it eliminates signal loss. Except for your "digital>analog>digital" story, that won't hold any ground. Conversions are ALWAYS lossy, be it digital or analog.

also, dvi can xfer/process larger amounts of data at higher speeds than vga.  this means better graphic output capabilities like faster framerates with better resolutions.


I seriously doubt that. As far as I know VGA, like RGB, doesn't have a bandwith limit. I don't believe framerates are an issue here. I have heard reports that DVI can better handle higher resolutions, but I think that again has to do with the signal loss, which becomes more noticable at higher resolutions. My 19" has a native 1280x1024, and I can certainly spot no difference.

I'm not arguing DVI is not better than VGA, there is no doubt that it is, I'm saying you'll only be enjoying it's benefits in specific cases (long cables, very high resolutions).

#7 ober

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Posted 09 October 2006 - 08:36 PM

Besides CV... you're going up against a PHPFreaks Recommended member... you're just a Global Mod *finger twirl* ;)

*snicker*

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#8 448191

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Posted 09 October 2006 - 08:40 PM

Besides CV... you're going up against a PHPFreaks Recommended member... you're just a Global Mod *finger twirl* ;)

*snicker*


LOL  ;D.... Don't start power playing me you brut...  :P

#9 .josh

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Posted 09 October 2006 - 08:45 PM

the point i was trying to make is that with vga there is always signal loss, whether you use a vga hookup to a crt monitor or a vga hookup to an lcd monitor, because of having to convert from digital to analog on the first, digital/analog/back to digital on the 2nd.  if you have an lcd monitor and a dvi connection, there is no such conversion, therefore no such signal loss.

I will agree that if you have a good quality short vga connection, then you probably won't notice the difference unless you have a really good eye, under most mundane circumstances. 

and i still disagree about the bandwidth.  all my research into it points to dvi having higher bandwidth capabilities than vga. 
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#10 448191

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Posted 09 October 2006 - 08:54 PM

and i still disagree about the bandwidth.  all my research into it points to dvi having higher bandwidth capabilities than vga. 


You may be right about that, like I said, as far as I know, VGA doesn't have a bandwith limit. I could be wrong. It wouldn't be the first time, LOL...  :P I recall it being more or less equal to RGB, which I KNOW doesn't have a bandwith limit.

Anyway, we're pretty much in agreement I feel.

#11 neylitalo

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Posted 09 October 2006 - 08:56 PM

Gentlemen, gentlemen... keep it above the belt, no biting, and just behave in general ;)
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#12 448191

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Posted 09 October 2006 - 09:19 PM

Gentlemen, gentlemen... keep it above the belt, no biting, and just behave in general ;)


I'm behaving, am I not?  ??? A friendly discussion never killed anybody. If I offended anybody (I don't see how), I appologize. Let's all grab a beer and make up, like men do (if there's anything to make up for - otherwise can we still have the beer? :P). 

#13 neylitalo

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Posted 09 October 2006 - 10:31 PM

I wasn't pointing fingers at anybody, really - I was just seeing the potential for some escalation, and wanted to stop it before it got much further. I apologize for implying that anyone was out of hand, it was more preventative medicine than anything.

And you go ahead and have the beer - I'll be the DD. :)
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#14 .josh

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Posted 09 October 2006 - 11:10 PM

lol, i didn't see this as some kind of potential 'confrontation' either.
Did I help you? Feeling generous? Buy me lunch! 
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#15 neylitalo

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Posted 09 October 2006 - 11:19 PM

sorry, guys... I guess I'll just have to add one to the number of times I've been wrong. I'd so hoped I wouldn't make it to double digits. :(

But the no biting rule holds. :)
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#16 ober

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Posted 09 October 2006 - 11:30 PM

*chomp*

Alright CV and 448191, I think we've duped neylitalo.  Back to the fight!

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#17 Daniel0

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Posted 10 October 2006 - 02:26 PM

So it would be fine to just stick with my VGA cable?

If I change the resolution to anything different from my monitor's native resolution (1440x900) the image looks grainy, would a DVI cable solve that?

#18 ober

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Posted 10 October 2006 - 02:36 PM

Native resolution is just that... it's going to look best at that resolution and probably crappy otherwise.  I don't think the cable will help much.

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#19 Daniel0

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Posted 10 October 2006 - 03:49 PM

Oh ok. I just wondered since on the old CRT monitors any screen resolution would look ok.

#20 ober

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Posted 10 October 2006 - 04:02 PM

LCDs are picky ;)

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