Quad Monitor Troubles

Nalrincay

Honorable
Jul 28, 2013
14
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10,510
I recently found an old VGA flatscreen around the house, and I thought I would try out four monitors. Whenever I try to enable the fourth monitor, it says "Unable to save display settings". Two of my monitors are the same resolution (1920x1080) and the other is 1360x768.The VGA I'm trying to connect is 1280x1024. I'm running all of these off a 270x with a bunch of adapters due to the stupid Displayport thing. Here's how I currently have it set up below:

Main monitor (1920x1080): DVI
Second 1920x1080: HDMI
1360x768: Active Displayport adapter
VGA: VGA to DVI adapter

Help is very much appreciated.
 
Solution


It's DisplayPort from the GPU to the adapter, and then HDMI from the adapter to the display? If so, that's exactly what I thought. Your having an R9-270X confirms my suspicions, the Tahiti and Pitcairn chips have only two pixel clock generators.

The Tahiti and Pitcairn based (HD 7800 series, HD 7900 series, R9-270 series, and R9-280 series) GPUs do indeed support 6 displays. The breakdown works as such:

Two displays using pixel clocks in combination with either analogue RGB component transmission (VGA) or TMDS component transmission (DVI/HDMI).

Four displays broken into two...


Hi,

VGA, HDMI, and DVI all require separately driven pixel clocks. DisplayPort does not (although if the DisplayPort is passively converted to DVI or HDMI it will).

I don't know what NVidia's limitations are, but most AMD graphics cards have only two pixel clock generators (the notable exception is the R9-290 and R9-290X, they have more). This means that the only way to drive three or more displays is for one or more of them to be driven natively by DisplayPort. It is possible to use an active DisplayPort adapter to convert the DisplayPort signal to another format, as the adapter itself generates the pixel clock.

If your graphics card has an unused DisplayPort or Mini DisplayPort port, you can connect an active adapter to this to drive the 4th monitor.
 


Which graphics card do you have?

Is the interface HDMI on the monitor and DP on the GPU, or DP on the monitor and HDMI on the GPU?
 


It's DisplayPort from the GPU to the adapter, and then HDMI from the adapter to the display? If so, that's exactly what I thought. Your having an R9-270X confirms my suspicions, the Tahiti and Pitcairn chips have only two pixel clock generators.

The Tahiti and Pitcairn based (HD 7800 series, HD 7900 series, R9-270 series, and R9-280 series) GPUs do indeed support 6 displays. The breakdown works as such:

Two displays using pixel clocks in combination with either analogue RGB component transmission (VGA) or TMDS component transmission (DVI/HDMI).

Four displays broken into two pairs, with each pair connecting to a DisplayPort host controller. DisplayPort does not require a pixel clock, and can be daisy chained.

An active converter can be inserted between a DisplayPort host and a display. The converter will generate the necessary pixel clock for the VGA/HDMI/DVI output. One of these active converters can be used on each port to bring the total number of VGA/HDMI/DVI displays to 4.

Supposedly the Hawaii based GPUs (R9-290 series) support more than two pixel clocks which allows for more than two displays to be connected via VGA/HDMI/DVI but I don't have one of these to test with.
 
Solution


You need to acquire a DisplayPort to VGA adapter. Use this on the second DisplayPort connector to attach the 4th monitor