DVI-D issue w/ two 27" 2560x1440 monitors

[prophets]

I’ve spoken to Gigabyte Tech Support, not much help really. I’m hoping for some feedback to figure out my best move.

I own:
- Gigabyte Radeon HD 6870 1GB Overclock Edition Card. Model #: GV-R687OC-1GD
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125357
- Asus P55 mobo w/ an i3 CPU.

I purchased:
- Two Shimian 27” QH270-Lite Monitors (QHD 2560x1440 resolution). Each monitor requires Dual-Link DVI-D connections.


Problem: I cannot get both monitors to work on the card. One monitor will output no problem on the top DVI-D output port (next to the HDMI/minidisplay ports). I believe it is because the card only has a single DVI-I output and a single DVI-D output and the monitors each require a DVI-D output.

I need suggestions on how to work around this problem. The card previously supported two 1920 x 1080 monitors without an issue.

- I could buy an adapter that converts the DVI-D monitor to HDMI or mini displayport. This requires an ‘active’ adapter to handle 2560x1440 and that’s extremely expensive, so if anyone knows a cheap way to do this, that would be helpful.
- I could buy a different graphics card. Any suggestions are welcome.
- I could buy a second graphics card (my mobo accepts 2 cards in crossfire scheme).

I don’t really game much, so pls don’t reply to this and tell me I need an i7-whatever-ultra mobo or I'm a total noob, etc.

 

[JJ1217]

Thats why I got this card as my master card:

http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=1160&pid=1654&psn=&lid=1&leg=0

Has two dual link DVI's, so I can push two Korean IPS panels if I wanted to, but I probably won't because it takes so much room.

You could buy a new card, a 6870 might struggle pushing two 2560x1440 monitors, and you would see maybe around 55 degree idle temps.

 

[MC_K7]

+1 for BigMack70

Exactly what I was going to say. Most cards don't have 2 x dual-link DVI ports and you need those if you want to get past 1080p. Also requires dual-link DVI cables. That's the first thing I would check.

 

[wanderer11]

You could try a minidp to dvi adapter, or if you can't find that minidp> dp and then dp>dvi. The picture of your card shows two dual link dvi ports, but I'm pretty sure only one can do dual link at a time.

 

[prophets]

Thanks for the thoughtful replies. Random Internet People On Toms Hardware > Gigabyte Tech Support.

1. The DVI-D cables are not the problem, nor are the monitors. I swapped them back and forth checking each piece of hardware. Also the cables came w/ the monitors.

2. The issue has been isolated to 1 specific DVI output port on the card.

I will probably evaluate buying the sapphire card.

 

[mindless728]

If the issue is on one port of the GPU, I would gander a guess that the port is single link only, hence the issue with that port

 

[gatortpk]

Thats why I got this card as my master card:

http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=1160&pid=1654&psn=&lid=1&leg=0

Has two dual link DVI's, so I can push two Korean IPS panels if I wanted to, but I probably won't because it takes so much room.

You could buy a new card, a 6870 might struggle pushing two 2560x1440 monitors, and you would see maybe around 55 degree idle temps.

I have a 6870, and I was wondering about if both DVI-I ports were indeed DL-DVI ports. I do know from experience that one DVI-I port is actually just a DVI-D though it will fit a DVI-I to VGA Adapter (but won't work on that port).

I find it interesting that you implied the HD 7850 to handle two 2560x1440 monitors much better. 870 is greater than 850, though 7000 is newer than the 6000 series, the 6870 can do 2,016 Gflops vs 1,761 Gflops on the 7850. The MPixels/second is also higher on the HD 6870.

It is true though, that the memory bandwidth is higher on the newer 7850 and probably most important is the 28 nm process vs the 40 nm process in the 6870. So it'll consumer much less power and be cooler.

But will the 6870 have that much more trouble driving two 2560x1440 displays than the 7850? Despite the overall higher performance of the 6870?

Of course the 6950 (and 6970/6990) or the 7870 will easily outperform the 6870 or 7850. Is there something I'm missing about the advantage of the 7000 series over the 6000 series?

Most importantly, can the 6870 drive both DL-DVI ports? The information was readily available on your link about the 7850 that the 7850 does indeed have (but drive?) both dual-link ports. Also, with the DisplayPort (v1.2), could either card drive Three 2560x1440 monitors? I'd like to try three displays in portrait mode. (I did find a good deal on two such displays and have a 27" iMac as a Target Mini DisplayPort display for the main/middle display)

Update: Upon further research, I find it unlikely that both DVI ports are actually DL-DVI. But using a Mini DisplayPort cable to the 27" iMac (in Target Display Mode) and another DVI 2560x1440 monitor should work find on either card. I still think the 6870 shouldn't have a problem with that? Also, I could use an active DisplayPort to DL-DVI adaptor and drive two DVI 2650x1440 displays. Do all the Active DisplayPort to DL-DVI adaptors work reasonably well now, or are they still hit or miss?

 

[bluismycat]

I know I am very late here but I will comment anyway.

I was running 3 x 27" 1920 x 1080 monitors on a gtx770. I wanted to upgrade to 2 x 27" 2560 x 1440 and 1 x 30" 2560 x 1600. The first 27" worked fine with the DVI cable. Neither the next 27" or the 30" would, however. DP and HDMI run the res but not the DVI-D I was trying.

Quite by accident I found out why.

It had NOTHING to do with the ports being single or double!

The cause of the problem I had was:- the DVI-D cables I was using were 3m cables. The cables supplied in the monitor boxes were 1m - 1.8m cables. DVI-D is supposed to drop down the resolution it can carry when it gets to 4.6m. In the case here, with 2 different brands of monitor...2 x AOC Q2770P and 1 x MTECH MT 30 WQXGA, the 3m cable is too long for the DVI signal to handle at 2560 x 1440. HD (1920 x 1080) is carried by the DVI D cable on 3 or 4 monitors not a problem. As you up the res, my advice is to drop the cable length.

I am now aiming for 3 x 27" @ 2560 x 1440 surround grouped together in a Thunderbolt daisy chain of 1 res of 7680 x 1440 with the 30"@ 2560 x 1600 sitting above and behind on the DVI-D. Will it work??? I am going to find out...

 

[wizardofid555]

I know I am very late here but I will comment anyway.

I was running 3 x 27" 1920 x 1080 monitors on a gtx770. I wanted to upgrade to 2 x 27" 2560 x 1440 and 1 x 30" 2560 x 1600. The first 27" worked fine with the DVI cable. Neither the next 27" or the 30" would, however. DP and HDMI run the res but not the DVI-D I was trying.

Quite by accident I found out why.

It had NOTHING to do with the ports being single or double!

The cause of the problem I had was:- the DVI-D cables I was using were 3m cables. The cables supplied in the monitor boxes were 1m - 1.8m cables. DVI-D is supposed to drop down the resolution it can carry when it gets to 4.6m. In the case here, with 2 different brands of monitor...2 x AOC Q2770P and 1 x MTECH MT 30 WQXGA, the 3m cable is too long for the DVI signal to handle at 2560 x 1440. HD (1920 x 1080) is carried by the DVI D cable on 3 or 4 monitors not a problem. As you up the res, my advice is to drop the cable length.

I am now aiming for 3 x 27" @ 2560 x 1440 surround grouped together in a Thunderbolt daisy chain of 1 res of 7680 x 1440 with the 30"@ 2560 x 1600 sitting above and behind on the DVI-D. Will it work??? I am going to find out...

God damn cable length. You are a god damn genius. That fixed it for me.