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Using Windows 7. I got a new Radeon HD 5830 video card with 1 DVI, 1 HDMI, and 1 DisplayPort. I'm trying to get two monitors working. First monitor connected to DVI port works. Second monitor connected to DisplayPort (via adapter) doesn't work. Also I've been reading something about active vs passive DisplayPort adapters. I'm not sure which I have and I'm not sure if that's it.

Any ideas? Should I get an HDMI to DVI adapter instead?

UPDATE

The plot thickens. I tried disconnecting my first working monitor and then connecting my second monitor, an LG W2361V Flatron, using DVI (instead of the DisplayPort as above). I fully expected this to work but it doesn't. The monitor works via VGA (hooked up to another computer) and also previously worked with DVI via DMS-59.

I got a spare monitor and hooked it up via the DisplayPort, and, voila!, I have two displays now. So presumably it's not a video card or adapter issue but a monitor issue. However, I'm thoroughly confused now.

My LG monitor says it's DVI-D if that makes any difference.

UPDATE 2

I found this site: http://www.avsforum.com/avs-vb/archive/index.php/t-1211892.html which seems to talk about a similar issue. I would agree that the monitor seems to be stuck in power saving mode? The red power light flashes on and off. So based on what I read at that link I booted windows in safe mode using my working monitor via DVI and then switched to using my LG monitor and lo and behold it displays an image. Progress! However from within safe mode I right clicked on the desktop and went to screen resolution. The resolution was set to 800x600 and when I clicked save to close the dialog box the monitor went blank (again appearing to go into power saving mode). It would not wake up despite key presses and mouse moves.

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Did you use Catalyst Control Center to detect and identify the second monitor? Did CCC understand the available resolutions of the 2nd monitor? –  Robert Kerr Aug 21 '11 at 17:31
    
Catalyst Control Center does not detect the second monitor (if the 2nd monitor is the LG) –  User Sep 15 '11 at 21:02

4 Answers 4

Based on your two updates, I would suggest that perhaps your video card is running that port higher than your monitor supports. For example, if you try to run a monitor at 1600x1200 and it only supports 1280x1024, it will look like it is going into sleep mode.

The trick is to find a resolution the monitor supports. What I generally do is, on the working monitor, right click and choose properties to go into the display settings, and select the secondary monitor, then change the resolution to the lowest setting and hit apply. If that setting doesn't work, go up one, and on and on until you find a setting that works or determine that the display won't work with the card.

It's also possible that the DVI reception circuitry is broken in such way, that it can handle lower bandwidth traffic but not up to what it should. VGA signal is interpreted in very different manner, being analog and all, so it's very much possible for DVI be broken while VGA works.

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I have seen a monitor fail so that it at first had problems coming out of sleep mode if using the highest bandwidth mode. With less demanding modes it worked fine at that point. So yes, it is possible for the digital side be half-broken so that some modes work, some don't. –  Zds Mar 19 '12 at 12:31

You could try this HIS HDPSDVIEYE DisplayPort to DVI Adapter AMD Eyefinity-Ready as I'm running 3 monitors one 1080p LCD Monitor and two 1080p LCD TVs from this Sapphire Radeon HD 5670 1 GB DDR5 HDMI/DVI-I/DP PCI-Express Graphics Card.

Since you only wanna run two monitors I think you should use (1) Native DVI and (2) cheaper HDMI to DVI (instead of more expensive DisplayPort to DVI)

My setup:

(1) DVI to HDMI: 1st TV is connected using this HDMI Female to DVI-D Male Video Adaptor

enter image description here

(2) HDMI: 2nd TV is connected using native HDMI port.

(3) DisplayPort to DVI: LCD Monitor is connected using this HIS HDPSDVIEYE DisplayPort to DVI Adapter AMD Eyefinity-Ready

enter image description here

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Without using CCC or Win-P second monitor will not show signs of "work"

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I had the same problem trying to connect my laptop to the LG W2361V. The laptop has a DisplayPort out, so I got a DisplayPort to HDMI cable. Black screen, power saver mode, even though Win7-32 recognized the monitor by name and everything. VGA cable works.

LG told me the HDMI port is only for TV use, not computer. I'd have to use VGA or DVI to use the monitor with a computer. Sounds kinda dumb, but at least that's an answer.

I'm going to get a DisplayPort to DVI cable. That should work.

I hope this information helps!

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I've since replaced the monitor but I am curious if the DisplayPort to DVI cable will work –  User Oct 5 '12 at 20:48

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