[RESOLVED] DVI-D to VGA-VBForums
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Thread: [RESOLVED] DVI-D to VGA

  1. #1

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    Resolved [RESOLVED] DVI-D to VGA

    Hi guys, wondering if anyone has any info that can help me out here.
    I just built a new pc which has a GeForce 1050TI video card in it.
    It has a display port, HDMI port and DVI-D port on it.
    I use a KVM switch with VGA cables and need to connect this card to it.
    I bought a DVI-D to VGA active adapter but when I connect it my display keeps going blank.
    Also when the display is active it appears a bit off and a little blurry.
    The adapter I got has no place for external power. I notice that some of them do but not this one.

    So did I just make a bad choice in which adapter to buy or is this an issue in general?

    Any suggestions as to how I can connect this card to my vga kvm and get a good quality 1920x1080 res out of it without spending a lot of cash?

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    Re: DVI-D to VGA

    Did you try a direct connection of the VGA signal to a monitor to eliminate the KVM switch as a possibilty for a degraded signal?

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    Re: DVI-D to VGA

    Quote Originally Posted by passel View Post
    Did you try a direct connection of the VGA signal to a monitor to eliminate the KVM switch as a possibilty for a degraded signal?
    No.. but I have other PCs connected and they all look fine. Pretty sure the adapter is the problem. I need it to work through the KVM.
    I can connect the PC directly to the display with HDMI and it works fine so long as the adapter is not connected to the PC. When the adapter is connected it causes the HDMI to also go blank every few seconds.

    I have also read on reviews where lots of people have mentioned slight loss of color and a little bit of blurry look with these active adapters.

    I have other cards where I use a DVI port but those do not require the use of an active adapter. They all work fine through the KVM with a simple adapter.

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    Re: DVI-D to VGA

    ! would suggest the first step is to connect the video card via dvi-d direct to the monitor as dvi-d using a dvi-d cable. If that works the issue is the dvi-d/vga adapter. If that doesn't then the issue is the video card. In the past I've had no problems doing what you are doing connecting dvi-d via passive vga adapter to kvm and then vga from kvm to monitor. Haven't used active dvi-d/vga adapter though - just simple passive ones with no problems.
    All advice is offered in good faith only. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/

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    Re: DVI-D to VGA

    Yep I have used the passive ones without issue as well. Apparently this new card requires an active one though. None of the passive ones I have will even plug into the port. No holes for the 4 pins near the - pin

    I do have another monitor here that I think has a DVI input on it but I do not think I have a DVI cable to test with. I'll take a look and see later. May try it connected direct to another monitor and lower res setting just to see what happens.

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    Hyperactive Member 2kaud's Avatar
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    Re: DVI-D to VGA

    None of the passive ones I have will even plug into the port. No holes for the 4 pins near the - pin
    The passive dvi-d to vga adaptors I have have a pin layout identical to a dvi-d plug from a dvi-d cable. So they fit any socket capable of taking a dvi-d plug. I haven't come across any passive adaptors that have a different pin/layout to a proper dvi-d plug.
    All advice is offered in good faith only. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/

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    Re: DVI-D to VGA

    All of the passive adapters that I have here and pretty much all of the ones I see online have the pins around the - pin some have just two pins there, others have 4 2 above and 2 below the - pin. The port on the card has no holes top or bottom there so they will not plug into it. Apparently as of the 1000 series there is no VGA port on any of the cards and the DVI port is different than it was on previous models. My passive adapters work on all the cards I have except this one.

    Any way I have decided to return the active adapter since even if I get the screen toggling corrected the picture is still below my standards and will not fly.
    I have ordered a passive Display Port to VGA adapter and will give that a try when it arrives.

    Edit: from everything I have saw online the passive adapters are for DVI-I I have both single link and dual link adapters for the DVI-I and one for DVI-A.
    Apparently the analog signal is using those pins above and below the - pin which are on all the DVI-I cables but do not exist on the new DVI-D sockets. From everything I read only an active adapter will work as it needs to convert digital to analog and the cheap ones do not seem to do a very good job, if they work at all.

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    Last edited by DataMiser; Aug 10th, 2017 at 01:00 PM.

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    Re: DVI-D to VGA

    After doing some more online searching I am not sure if the DP>VGA adapter will work or not. It did have 3 reviews and all 3 said it worked so I'll keep my fingers crossed it was only $10 so no biggie. Looks like the active adapters that may actually be any good are going to be at least $30 or more.

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    Hyperactive Member 2kaud's Avatar
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    Re: DVI-D to VGA

    Thanks for the info. That's very interesting. I didn't know there were all these variations! You learn something everyday. I've looked at ours and all are DVI-D Dual Link. These work well with passive VGA adaptors.
    All advice is offered in good faith only. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/

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    Re: DVI-D to VGA

    Really? Where did you manage to find a DVI-D passive adapter? I scoured newegg and amazon for hours and did not find one.
    Correction I did find one on new egg but 79% of the people who bought it said it did not work.
    Last edited by DataMiser; Aug 11th, 2017 at 07:48 AM.

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    Re: DVI-D to VGA

    Amazon.co.uk. There are several. They have a poor rating with many reviews saying they do not work, but we've had no problem. Mind, we've using quite old monitors/graphics cards (at least 8 years old) with them so this may have something to do with it.
    All advice is offered in good faith only. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/

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    Re: DVI-D to VGA

    Quote Originally Posted by 2kaud View Post
    Amazon.co.uk. There are several. They have a poor rating with many reviews saying they do not work, but we've had no problem. Mind, we've using quite old monitors/graphics cards (at least 8 years old) with them so this may have something to do with it.
    I have a feeling that is the case. I had not saw any cases where mine did not work until I got the new card. Apparently in the GeForce line the 700 series was the last that offered a VGA port on any of the cards, all the models which offered a VGA port would work with the DVI adapter no matter if there was actually a VGA port on the card or not. The new ones though are an issue.

    I haven't checked Amazon UK but the one here mixes the reviews so one has to be very careful. The active adapter I bought had a couple of good reviews listed and by people who were doing exactly what I am doing but then after it did not work properly I went back and looked at the reviews again and the good review was for a different product.
    Last edited by DataMiser; Aug 12th, 2017 at 02:08 PM.

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    Re: DVI-D to VGA

    Quote Originally Posted by DataMiser View Post
    Really? Where did you manage to find a DVI-D passive adapter? I scoured newegg and amazon for hours and did not find one.
    Correction I did find one on new egg but 79% of the people who bought it said it did not work.
    I don't see how you could have a DVI-D passive adapter.
    The VGA analog signals come through the four pins at the bottom of the DVI-I and DVI-A connectors and those can be passively passed through to the appropriate pins of a VGA 15-pin connector.

    If you have a DVI-D connection, you don't have any VGA analog signal to pass through, you only have the digital signals.
    The adapter has to have circuitry to decode the digital signals converting them to analog and recreate a VGA compatible signal itself. That can't be done passively. Passive usually means the signals in and out are close enough that the connector only needs to remap the signals from the pins of one type of connector to the pins of another type of connector, such as between DVI digital signals and HDMI digital signals, with perhaps some passive conditioning components in line like resisters, capacitors or coils.

    Perhaps the device that doesn't work too well is misusing the term to mean that it doesn't require external power as it thinks it can draw enough power from some pins of the connector to power the circuitry needed to do the conversion. Obviously that doesn't work well. Perhaps if you were running at 640x480, i.e. the "true" VGA defined resolution it would work.

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    Re: DVI-D to VGA

    Quote Originally Posted by passel View Post
    I don't see how you could have a DVI-D passive adapter.
    The VGA analog signals come through the four pins at the bottom of the DVI-I and DVI-A connectors and those can be passively passed through to the appropriate pins of a VGA 15-pin connector.

    If you have a DVI-D connection, you don't have any VGA analog signal to pass through, you only have the digital signals.
    The adapter has to have circuitry to decode the digital signals converting them to analog and recreate a VGA compatible signal itself. That can't be done passively. Passive usually means the signals in and out are close enough that the connector only needs to remap the signals from the pins of one type of connector to the pins of another type of connector, such as between DVI digital signals and HDMI digital signals, with perhaps some passive conditioning components in line like resisters, capacitors or coils.

    Perhaps the device that doesn't work too well is misusing the term to mean that it doesn't require external power as it thinks it can draw enough power from some pins of the connector to power the circuitry needed to do the conversion. Obviously that doesn't work well. Perhaps if you were running at 640x480, i.e. the "true" VGA defined resolution it would work.
    Yep.. That makes sense. When I bought the active adapter I had read the reviews but Amazon mixes multiple products together and the review I actually read was for a model that uses a USB connection for additional power. Of course the one I bought claimed it could do 1920x1200 res so according to the product info it should have worked at 1920x1080.

    I also think you are correct on the DVI-D and passive adapters. All of the other cards I have have the 4 pinouts required for analog signal and all work fine. These are not present on the new card which is truly DVI-D.

    My hope is that the passive Display Port to VGA will actually work but I have my doubts about that one as well. Will be here sometime next week so will find out then

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    Re: [RESOLVED] DVI-D to VGA

    Surprisingly I received the DP>vga passive adapter today. I thought for sure it would not be here before next week. So I hooked it up and gave it a try. Works fine

    For any others who get one of these new cards and want to use a VGA display this is what I found.

    Passive DVI to VGA does not work at all
    Cheap active DVI-D to VGA without external power do not work at 1920x1080 res. May work at lower res but I did not try to see as I want to use 1920x1080
    More expensive DVI-D to vga with USB power should work but picture quality takes a small hit, slightly blurry and a bit darker.

    The cheap Display port to VGA passive adapter works much better than either of those.
    The link below is the item I ended up with and for under $10 with free shipping seems like the way to go.
    Only draw back is it does not have a way to screw the vga cable to it.

    https://www.newegg.com/Product/Produ...tent-_-text-_-

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