Multiple Display Problem with Radeon HD6870

[icsamis]

Hi,

I am having a problem with one of my designer's workstations. The workstation was ordered and then after-market we added the high end GFX card, which in this case would be the Radeon HD 6870. Initially it was setup with an Acer 23" Widescreen H233H as the primary display and a Dell 1905 19" standard monitor as the secondary display. Both of these connections were via DVI.

This has worked fine ever since.

We decided to make the displays equal and ordered a second Acer H233H widescreen to replace the Dell along with a dual monitor stand to arrange them side by side.

So, after disassembling everything, setting up the stand, and re-connecting, I was surprised to see that BOTH displays are reporting No Signal.

If I only connect the one, it works fine. As soon as I connect the second DVI, both monitors instantly go black. At that point, even if I remove the second, the primary remains black until rebooted.

I also seem to recall that before I re-connected everything, the primary was set to "Basic 1920x1080" in CCC. That option is no longer present and instead it defaults now to HDTV 1080p, with the highest Basic supported being 1680x1080 or something along those lines.

Can anyone help? I am running the latest and greatest CCC. Any input would be greatly appreciated, I cannot recall ever seeing behavior like this. Thank you.

 

[vacunita]

I could guess 2 possibilities:

1. The gfx card isn't getting enough power to run both monitors. Probably not but still with a check, if you still have the other monitor around check with it.

Also do both monitors work correctly by themselves?

2. The resolutions that were set for the dual display cannot be displayed by the monitors. Either because refresh rate is to high, or simply the resolution values are not within the monitors rage.

If you boot with both monitors connected do they display anything or will only one of them display, or nothing at all?









----------------------------------
Phil AKA Vacunita
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Ignorance is not necessarily Bliss, case in point:
Unknown has caused an Unknown Error on Unknown and must be shutdown to prevent damage to Unknown.

Behind the Web, Tips and Tricks for Web Development.

http://behindtheweb.blogspot.com/

 

[icsamis]

Well the card has all the power connections connected and is running off of a huge power supply, so I imagine it has all the power it needs.

Yes, I can get either to work independently.

They are the same monitor so if I can get the resolution on one, I would think I should be able to get it on the other.

If I boot with both connected neither works.

I was reading more online and it seems that one of the DVI ports on the card is single link and the other is dual link, could this be the culprit perhaps?

In the working configuration the 19 was only running at 1280x1024, whereas I am now asking the secondary to run 1920x1080 like the primary. Do you think it just might be too much for the single link port?

The card has two mini-displayport connections, I was thinking these might work better but I would have to order active dongles to do this and I would prefer to have some degree of certainty before ordering additional parts.

 

[vacunita]

I was reading more online and it seems that one of the DVI ports on the card is single link and the other is dual link, could this be the culprit perhaps?

Hmm, perhaps. If the Monitors require the second set of signals provided by the dual link port. Though that would not account for the other monitor powering off also.

Have you tried to update the GFX card's drivers from the Manufacturers website? It may be simply a driver issue that was resolved in subsequent versions of it.





----------------------------------
Phil AKA Vacunita
----------------------------------
Ignorance is not necessarily Bliss, case in point:
Unknown has caused an Unknown Error on Unknown and must be shutdown to prevent damage to Unknown.

Behind the Web, Tips and Tricks for Web Development.

http://behindtheweb.blogspot.com/

 

[BadBigBen]

are both monitors DVI-D? or are they VGA attached over a DVI-VGA adapter?

simply said, the upper port is a full DVI-I (digital and analog signals) port whereas the bottom is ONLY DVI-D (digital)...

Dual Link has nothing to do with this at all... Dual Link only comes into play when you attach a monitor with a resolution of 2560 x 1600...

Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[icsamis]

They are both DVI. There are no adapters being used.

Thanks for clearing up that dual link question.

 

[BadBigBen]

ok...

when you power on the system, does it show the POST screen on both monitors, or only on the one attached at to the top DVI port?

also check with the manufacturer if there is a firmware (video BIOS) update...


Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[icsamis]

It wasn't showing a post on either with both connected. Totally dead.

However, I did solve the problem by moving one monitor to a mini-DP port on the card using an active DVI/DP adapter.

With one in the DVI and the other in a DP it works as one would expect it to.

 

[BadBigBen]

well, I am glad you solved the issue...

but it is still strange that it would cut the signal to both DVI ports...


Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"