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-   -   Single vs Dual Link DVI (argh!) (https://www.hardwarecanucks.com/forum/video-cards/43830-single-vs-dual-link-dvi-argh.html)

hfxmike June 1, 2011 05:31 PM

Single vs Dual Link DVI (argh!)
Hi, I posted about the mysterious 6870 card...It arrived today and 9" was the limit for my case. phew.
Now the bad/annoying news.

I was running 3 VGA LCD monitors off a 5770 with no problems. 1 VGA->DP and 2 VGA ->DVI.

Popped in the new 6870 and only the top DVI port outputs a signal. Ahhh progress.
So...single link DVI is new, but doesn't output anything through a VGA adapter?

Reading around it seems that the only way I can run three monitors from the new card is by using one and ONLY one DVI (the dual link one). Then 2x miniDP or 1 miniDP + 1 HDMI (via another adapter).

Is this correct? or can I somehow use both DVI ports? (they look identical - like the bottom image - dvi-i dual link)

any help appreciated
ps -
Here is ATI's helpful clarification from the manual:
Single-link DVI-D connection. Provides video digital signals and HDMI™
output that is compatible with most HDMI-compliant devices.
Dual-link DVI-I connection. Provides video digital signals and HDMI
output that is compatible with most HDMI-compliant devices.


Mook06 June 1, 2011 10:43 PM

just for reference, the 4 pins with line between them on the left side of your diagram are the analog signal pins, both single link and dual link dvi support vga output as for why you get no signal, i am not sure, some dvi outputs simply dont output the analog portion (most onboard dvi for example)

have you ruled out dvi-vga adapter, cable and monitor as the problems?

hfxmike June 2, 2011 08:23 AM

The problem is that the card has a DVI-D (digital only - no signal for VGA) and DVI-I (I= integrated (digital + analog).

They pump Eyefinity and then they take away usable video output ports. :censored:

My adapters work fine on my 5770.

Eldonko June 2, 2011 08:34 AM

Maybe Im not understanding the issue but cant you use a DVI-I to HDMI?


hfxmike June 2, 2011 08:46 AM

I have 3 VGA monitors (1920x1080 LCDs, but VGA)

Teal3800 June 2, 2011 10:48 AM

WOW I didn't know they made 1080p monitors with no DVI.

Eldonko June 2, 2011 11:53 AM

Yeah that is weird. My monitors have no dvi but they have hdmi and vga.

hfxmike June 2, 2011 01:02 PM

they are cheap emachines monitors. work great.

i don't understand why the video card would have a DVI-D connection. Do they save that much money by shorting out the analog connectors? Why not keep both as DVI-I?

SKYMTL June 2, 2011 01:23 PM

The reference HD 5770 design didn't have a VGA port either and NOTHING has changed in terms of output connectivity on the newer cards.

For 3x VGA monitors, you still need to do the following:

Insert the following:

2x DVI to VGA adaptors
1x Passive DisplayPort to VGA adaptor

You CANNOT use a HDMI to VGA adaptor while using two DVI ports. This is due to the fact that DVI and HDMI both use the card's RAMDACs of which there are precisely....two.

Once this is done, you can go into the control panel, create an Eyefinity Group and go from there.

hfxmike June 2, 2011 01:36 PM

How could this DVI-D -> VGA adapter work? :
VGA 15 Pin Female to DVI-D Male Adapter Converter LCD | eBay

For $1 this has a DAC inside? The DVI-D port doesn't do analog. Which begs the question - What is the advantage of dvi-d over dvi-i?

I went from a 5770 to a 6870 and lost a monitor. : (

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