Display interface question DVI, DpsilayPort, VGA

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  1. Posts : 228
    Windows 10 home
       #1

    Display interface question DVI, DisplayPort, VGA


    OK, I've spent a lot of time on computers over the years but I never looked into display interfaces until I had to figure out how to connect a second display to a computer with only 1 VGA port and no room for a video card for a project my wife is involved in. I believe the DisplayPort to VGA adapter I have ordered will solve that but it has started me thinking about my own system: I have a Lenovo M58P with a Dell E2314Hf 23" monitor (I occasionally work with graphics for my Shirt Shop ). Not knowing any better, I connected them with the VGA cable that came with the monitor but I have never been truly happy with the display.

    The computer has a DisplayPort and a VGA port. The monitor has a DVI-D dual link port and a VGA. Would I be better off to keep using the VGA or to get a DisplayPort to DVI-D cable?
    Last edited by Sidecar Bob; 22 Nov 2020 at 19:08. Reason: spelling
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  2. Posts : 4,173
    Windows 11 Pro, 22H2
       #2

    VGA is an analog video standard. Any of the digital display types (HDMI, DisplayPort, the DVI-D) should give you better results, even at the same resolution.
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  3. Posts : 265
    Windows 10 Enterprise
       #3

    The displayport to DVI-D would be the way to go.
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  4. Posts : 228
    Windows 10 home
    Thread Starter
       #4

    Thanks.

    Since VGA monitors had sharper resolution than the ones with RCA inputs (remember those TV studio quality JVC video monitors re-branded as Commodore?) and I knew the ones with RCAs were analogue I thought that VGA was digital until today. You learn something old every day ;-)
    When I learned that DP, DVI and HDMI were all digital and VGA was analogue this afternoon I knew that any of the digital standards would be better but I wasn't sure if adapting between standards would make the result less good than VGA.

    After I read your replies I remembered that the other M58P I have is connected to a 43" TV with a VGA cable. That TV has HDMI inputs as well as the VGA; Is it safe to assume that a DP to HDMI cable would be better there?

    I hope so because I just ordered the DP to DVI and DP to HDMI cables...
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  5. Posts : 13,896
    Win10 Version 22H2 Pro and Home, Win11 Pro and Home
       #5

    If replacing a monitor one might look for similar features to one like what I was given [client was moving far and didn't want to ship it], it's a 27" ASUS that has 4 input types, VGA, DVI, HDMI and DisplayPort, a button on it's case selects as desired.
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  6. Posts : 228
    Windows 10 home
    Thread Starter
       #6

    The cables came today. The DP/DVI cable seems to work OK on my main computer with the 23" monitor. I don't see much difference looking at a page like this or even pictures but it does look better when watching a YouTube video on full screen.. Unfortunately I'll have to wait for another cable to arrive before I can try it more because that one has been hijacked for another project
    Need help getting 2nd display to work (HP 6005 USFF)

    I have 3 problems with connecting the 43" TV to the other computer with the DP/HDMI cable:
    1) The desktop is too big. Settings says it is still 1920 v 1080 (the same as with the VGA cable) bit the edges are off of the screen. I only see half of the taskbar, about 1/3 of the icons on the left side of the desktop are missing and if I maximize a window I lose the scrollbars. If I change to the next lower resolution the image is too small for the display (wide black area around the edge). I can't find anything in the TV's settings or in Windows to fix that.
    2) The text looks very bad. I am hoping that setting up ClearType will fix that.
    3) There is no audio. I use a small stereo amp with a pair of bookshelf speakers connected via the audio output on the back of the computer. When the TV is connected with the VGA cable I hear the sound from the speakers but when it is connected with the DP/HDMI cable there is no sound.
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  7. Posts : 4,453
    Win 11 Pro 22000.708
       #7

    Sidecar Bob said:
    The cables came today. The DP/DVI cable seems to work OK on my main computer with the 23" monitor. I don't see much difference looking at a page like this or even pictures but it does look better when watching a YouTube video on full screen.. Unfortunately I'll have to wait for another cable to arrive before I can try it more because that one has been hijacked for another project
    Need help getting 2nd display to work (HP 6005 USFF)

    I have 3 problems with connecting the 43" TV to the other computer with the DP/HDMI cable:
    1) The desktop is too big. Settings says it is still 1920 v 1080 (the same as with the VGA cable) bit the edges are off of the screen. I only see half of the taskbar, about 1/3 of the icons on the left side of the desktop are missing and if I maximize a window I lose the scrollbars. If I change to the next lower resolution the image is too small for the display (wide black area around the edge). I can't find anything in the TV's settings or in Windows to fix that.
    2) The text looks very bad. I am hoping that setting up ClearType will fix that.
    3) There is no audio. I use a small stereo amp with a pair of bookshelf speakers connected via the audio output on the back of the computer. When the TV is connected with the VGA cable I hear the sound from the speakers but when it is connected with the DP/HDMI cable there is no sound.
    At a guess, the TV is set to overscan. That makes sure the edges of the screen look good. (Seems unnecessary for a modern flat panel TV, but it's probably the default.) On my LG TV, overscan is eliminated by turning on "just scan". I see no mention of what TV you are using, so I can't look at the manual to find out how to turn off the overscan.
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  8. Posts : 228
    Windows 10 home
    Thread Starter
       #8

    It is an older Samsung flat screen, model LN40A500 (I guess it is a 40", not a 43). I remembered seeing "Just Scan" in the settings so I looked again, turned it on and the image now fits the screen. While doing that I plugged in both cables and when Windows detected it as 2 displays I set it to duplicate so I can switch between them with the TV's Source button and the edges of the screen now look just about the same for both.
    Thanks.

    And between that and going through the ClearType setup the text is somewhat improved. It is still more pixelated on the HDMI input than it is on the VGA but it is much better than it was. Maybe the VGA is just fuzzy enough to camouflage the pixelation?
    This one is usually viewed from about 10 feet anyway so this will probably be OK.

    And I figured out why I didn't have audio: I had audio when it was set to the VGA or TV (antenna) input but not when it was set to the HDMI input. I had found information online about sometimes having to go into the sound settings because plugging something into a DP can prompt the computer to assume you are using a digital audio device that is connected to that but I the only device in the sound settings was Speakers (High def audio device), which was the same as showed when it was on the VGA input and the sound was working. Besides, the almost identical computer (AFAIK, only the HDD is different) that I tried the DP/DVI cable with has a similar setup and it's audio worked.

    Then it occurred to me that I was hearing audio through the amp & speakers when it was set to TV. Hmm.... How is it doing that if the computer's audio output is plugged into the amp?
    Turns out I had the computer's audio output plugged into the TV's audio input and the TV's audio output plugged into the amp. Now that I think about it I did occasionally watch broadcast TV on it when I set that up but stopped doing that when the TV's remote stopped working (probably needs a good cleaning) and I couldn't change inputs from across the room and my speakers sound a lot better than the TV's so I guess it made sense to connect it that way at the time.
    And I guess the TV's audio input must only work when it is set to the VGA and the DP/HDMI cable isn't carrying audio to the TV.

    So I found the right cable to connect the computer directly to the amp and I now have audio when I'm using the DP/HDMI cable for the video.

    Cool. Now I need to order another DP/DVI cable......
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  9. Posts : 228
    Windows 10 home
    Thread Starter
       #9

    Nothing I tried made the text look right on the TV/computer setup with the DP/HDMI cable so after a few days I went back to the VGA connection because it looked better (maybe because it is an old TV?)

    The DP/DVI cable I ordered for my main computer came a few days ago and it is definitely better connected that way so I'm going to mark this one Solved.

    Thanks again.
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  10. Posts : 231
    Windows 10 Home 21H1
       #10

    You don't need to revert to VGA. I'm using HDMI on my 2008 Samsung LCD TV and it's working great. You just have to get the refresh rate, scaling, dpi and color encoding right. And of course the resolution. You want to go with the native res or lower. If it's not full hd then go with 720p for example.

    Dvi and display port are similar in this case ti HDMI. They are all digital and you can convert between them with an active adapter with minimal to no quality loss.

    This is not true for vga though. Vga is an old, lossy analogue signal that should just, die. For good.

    Depending on your device, you can get amazingly high refresh rates and special color encodings and a right screen spanning with applying just the right combination of settings for any of these digital interfaces.
    You can't do these with vga. That dinosaur can only do 60hz at 1920x1080 if i remember correctly. It maxes out there and even there it is visibly blinking and flashing as it refreshes. The digital ones with a high refresh rate don't do that. I hope this helps.
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