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-   -   dual monitors, DVI & displayport (http://www.nvnews.net/vbulletin/showthread.php?t=161349)

obc3d 04-08-11 02:56 PM

dual monitors, DVI & displayport
I'm running LINUX SUSE w/ a Quadro 4000, 260.19.44 driver & (2) 1920x1080x120Hz monitors for shuttering 3D visualization.The primary monitor is DVI to DVI; 2nd monitor is DisplayPort to DVI (board to monitors). When logged in as root, I can use the X Server settings tool to configure TwinView & the 2nd monitor to the correct 1920x1080 res, but not 120Hz. Secondly the 2nd monitor config goes away if I log out of root & log back in as me (for accessing a particular program). The 2nd monitor then comes up in low-res, but the TwinView is intact.
Should both monitors be connected as DVI-D, using a DVI splitter? The xorg.conf appears to be properly populated, except for no refresh rate for DFP-1 (2nd monitor). I've tried adding various options to the config file to force the rate etc, all to no avail. Anybody got any tips?

frenchy2k1 04-11-11 12:11 PM

Re: dual monitors, DVI & displayport
What type of Adapter do you have?
You need a Dual DVI to reach 120Hz refresh: (from wikipedia: http://en.wikipedia.org/wiki/Digital_Visual_Interface)

The DVI specification mandates a maximum pixel clock frequency of 165 MHz. With a single DVI link, the highest supported standard resolution is 2.75 megapixels (including blanking interval) at 60 Hz refresh. For practical purposes, this allows a maximum screen resolution at 60 Hz of 1,915 1,436 pixels (standard 4:3 ratio), 1,854 1,483 pixels (5:4 ratio), or 2,098 1,311 (widescreen 16:10 ratio).

To support display devices requiring higher video bandwidth, there is provision for a dual DVI link. A dual link doubles the number of TMDS pairs, effectively doubling video bandwidth at a given pixel clock frequency. The DVI specification mandates how the dual link may be used. All display modes that use a pixel clock below 165 MHz, and have at most 24 bits per pixel, are required to use single-link mode. All modes that require more than 24 bits per pixel, and/or 165 MHz pixel clock frequency must use dual-link mode. In dual-link mode, and in modes using 24 bits per pixel or less, the transmitter stripes pixel data across both links; each sequential video pixel is transmitted on alternate links. In modes with color depth greater than 24 bits per pixel, the second link carries the least significant bits of each pixel.
My guess is that your DisplayPort adapter is only a passive single link. You'll need a double link DVI adapter (rare) to run 120Hz.

Not sure about config and root, but check permissions on your files and make sure your personnal login can read those.

obc3d 04-11-11 03:40 PM

Re: dual monitors, DVI & displayport
Thanks Frenchy2k1,
DisplayPort - DVI-D cable is from CablesToGo. Their description is below.

I did a test & swapped cables/monitors. Whichever monitor is running from the DisplayPort can display the 1920x1080 but NOT 120Hz. You're hunch about passive may be the culprit.
Any suggestions on where to find an "active" DisplayPort to DVI-D cable?
nVidia Quadro 4k literature notes: Dual DisplayPort (...up to 1920x1200 @ 120Hz).
Must be my cable?
Will a DVI-D splitter work or is that just going to give me a clone on 2 monitors?

Thanks for the advice regarding config & root. I'll check permissions, etc.

CablesToGo: http://www.cablestogo.com/product.as...=152&sku=54183

Use this DisplayPort to DVI cable to connect a DisplayPort source directly to a DVI monitor or display. The passive design will support a 1920 x 1080 resolution up to 3 meters. It is VESA-compliant with transparent operation which will auto-calibrate and configure the signal for minimal configuration. Great for applications when you want to connect a newer laptop or desktop to a DVI-enabled display.

Connector 1: DisplayPort Male
Connector 2: DVI-D Male

Please Note: This DisplayPort adapter operates passively and is designed for use with dual mode graphics cards often designated with D++. Although the vast majority of source devices with DisplayPort are dual mode, it is recommended that you consult with your computer or graphics card manufacture to verify compatibility with passive adapters.

danix 04-11-11 03:42 PM

Re: dual monitors, DVI & displayport
If you decide to use an active DP->dual link DVI adapter with 3D VIsion displays that require display authentication, make sure that your adapters support DDC so that the authentication will work.

Here's a known good adapter from Bizlink:


danix 04-11-11 03:44 PM

Re: dual monitors, DVI & displayport
Note that older Bizlink active adapters do NOT support DDC. Make sure that you are purchasing the DDC capable version if you decide to go this route.

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