Video card with 2 ports (1: vga 2: dvi) not running 2 monitors properly

Question

I have an AMD Radeon HD video card. Not sure if it is 6750 or 6950.

It has two ports on it: one is VGA and one is DVI.

Currently I am running 1 monitor out of the VGA input.

I want to run the same monitor out of the other input and I bought a DVI to VGA adapter but the second monitor is not registering. It powers on fine, but the computer does not recognize that it is connected. I've tried to do a little research and have found people that suggest a "converter" to convert the signal coming out of the DVI port to a VGA signal and that will make it work. Others have suggested buying a DVI monitor instead.

Are these correct options? My only options? I'm a little lost as to how to get this to work.

---

So I checked. I have a AMD Radeon HD 6670 card. I think the second port is actually a displayport and not DVI. Seeing as I don't know what this is I don't think my DVI to VGA adapter works in that port. It fits though. This is what the back of my card looks like: http://www.pcmag.com/article2/0,2817,2385800,00.asp

Second edit...it's not a displayport it's an hdmi port.

Solution 1

Your graphics card should support being able to drive both a VGA and a DVI monitor at the same time.

ATI have a (slightly rubbish) guide on the basic steps to get it to work with the two monitors ATI Multimonitor Guide. Basically the show you how to run their setup wizard.

In the ATI Catalyst Control Centre you should see something similar to this, though I've no idea how old this image is what you are looking for should have a similar name:

Basically if your second monitor is being detected then you can enable it.

If on the other hand the monitor is not able to be detected you may need to check your connectors and cables to make sure they are all well seated. Possibly try booting the machine with only the VGA monitor connected to see if it works at all.

-=EDIT=-

Having re-read your question I think I understand your problem a little better. You are using the VGA output on your graphics card, and using the analogue output from the DVI port via a DVI-VGA adapter.

I'm still a little surprised that this did not work but it is entirely possible that the graphics card only has one set of hardware for converting the digital video signal to analogue VGA and so will only work with one VGA monitor at a time. This would mean you can use either the VGA or the DVI-VGA but not both.

I have a graphics card here that has two DVI ports, but only one of them will accept a DVI-VGA converter, the holes for VGA are missing so the connector cannot be plugged in so I guess this card would have the same problem you are experiencing, only one analogue monitor output.

Another thing to check though is if your graphics card has a DisplayPort output. If so you can get adapters to convert that to a VGA output. I have just recently had reason to buy a Displayport to VGA adapter which worked a charm for driving an old VGA monitor and it was cheap at £5 all in.

It seems that digital DVI to VGA converters are expensive (£100+) while digital Displayport to VGA converters are much cheaper at <£20.

Solution 2

I have the same card - and tried the same set up as you.

It doesn't work.

Your DVI port is a DVI-D which is digital only and will not support your DVI-to-VGA adapter since there's no analog signal to adapt.

I am running 2 1080p HDMI TV's - both of which have VGA inputs and cannot run both as VGA.

You can only run ONE VGA display with this card.

However - if your monitors are actually TV's too and have HDMI or other similar digital inputs you can run both with your 6670 card at the same time.

My set up is 1 x HDMI to HDMI cable and 1 x DVI to HDMI adapter cable.

So basically I'd recommend you forget about using VGA at all.

Instead - use your HDMI and your DVI connections as ( depending on your monitors ) you can get FULL 1080p ( 1920 x 1080 ) resolution on both monitors which is far better picture quality than a VGA connection will often allow.

Comments

[Linger]

Are you sure that the video card supports dual monitors? Even though it may have two connections, it may only support one monitor.

[ganesh]

Can you add which card you are using? Iinclude the brand and the precise model. If it is the reference AMD card then they should have at least four ports on it. Also, connecting the same monitor to the other port? Or a second identical monitor? If you have two monitors, which inputs do they accept? (VGA input is truly old and usually only found on very old monitors or on budget monitors).

[ganesh]

The AMD site will say it works because it works for their card. (The ones with the shroud and 4 or 5 display plugs). However other manufacturers use AMDs chip to make their own cards and they can be quite different. Just try a google images on 7950 and see much some of the models differ from each other. Also, you can edit your original post to add more information (delete this post later, after you got home and added the info to the OP).

[Joel Coehoorn]

The problem is he has two monitors that only have vga connectors, and so needs to get the dvi port to pretend it's a vga port, and cable that will match that.

[Mokubai]

Ah, I missed that, he has 1 x VGA port and is using another DVI->VGA adapter for the other monitor. Hmmm, that's a curious one.

[David Schwartz]

If it's a DVI-D port, it won't work with a DVI-to-VGA adapter since there's no analog signal to adapt.

[Marcus Chan]

I thought I read somewhere that most graphics cards only support one analog output at a time (as Mokubai said, "the graphics card only has one set of hardware for converting the digital video signal to analogue"), but I couldn't find it again.