I'm a scrub, help me understand this please..

[Tobit]

I'm ashamed, I have no excuse other than I've been too broke to play with shit and getting old. However, I have not been keeping up on the times and I really don't understand what is going on. Could someone please help educate me as to what is going on and advise the best way to connect these two monitors?

Background: I just upgraded from a GTX260 to a GTX970. I have *always* had both monitors plugged into both DVI ports on the GTX260. However, when I went to use both DVI ports today, only one monitor would be recognized at a time regardless of which port I plugged it into. On this GPU, one port is a DVI-D and the other is a DVI-I. The GPU also has 3x display ports and 1x HDMI.

The monitors are cheap Dell units, one is an S2409W and the other is an ST2421L. I don't know what type of DVI they support, the only specs I can find just make a general reference to having a "DVI" port. They both also have HDMI and VGA ports.

I was finally able to get both monitors working together, one with a DVI and one with an HDMI cable. However, I was getting a lot of red pixel dots and lines on the monitor with the DVI cable. I took a good look at the cable and determined it to be a DVI-D single link. I swapped it for the only other cable I had, a DVI-D dual link, and it cleared up that problem.

I'm not pleased with the image quality of the monitor connected to the HDMI port presently, it seems way too bright and the contrast is way off and I can't seem to find a happy balance with the on screen controls. It almost looks washed out. On the other hand, the monitor connected via the DVI-D dual link to the DVI-D port on the GPU looks excellent.

I can't upgrade monitors at this time so I'm wondering what is the best way to be connecting both of these for now.

Any guidance would be appreciated, thanks for reading and your time.

 

[Deleted member 89018]

I believe the first problem (only one DVI output working at a time) is something in all 970s - I seem to recall reading somewhere that it's set up to allow use of only one at a time, but can't find a link about it now.

As for the second problem, the red dots and lines, that may not have necessarily been because it was a single-link cable vs a dual-link cable - single link would be plenty of bandwidth for the monitor's native res. Did you get the red dots out of both DVI ports or just one? I've seen that before when a cable goes bad / is bad / doesn't have a good connection somewhere along the line.

Lastly, the contrast being off and all that - somewhere in the nvidia driver settings there's an option to make sure it is sending full RGB over HDMI. I believe by default it assumes that an HDMI connection is going to a TV, so it doesn't send the same color data it would send over DVI to a PC monitor. I don't have my system in front of me right now to find the setting though (currently on a laptop), perhaps someone else could chime in as to the location.

A displayport to DVI adapter may also eliminate the issue.

 

[Tobit]

As for the second problem, the red dots and lines, that may not have necessarily been because it was a single-link cable vs a dual-link cable - single link would be plenty of bandwidth for the monitor's native res. Did you get the red dots out of both DVI ports or just one? I've seen that before when a cable goes bad / is bad / doesn't have a good connection somewhere along the line.

I had not switched ports, just cables and it immediately solved that problem. I can even replicate it going back to the other cable. the problem, however, started as soon as I got both monitors working on the DVI-D and HDMI port.

The only dual config I can get working right now, actually, is DVI-D+HDMI. DVI-I+HDMI doesn't work, only the HDMI connected monitor is recognized.

 

[Tobit]

ILastly, the contrast being off and all that - somewhere in the nvidia driver settings there's an option to make sure it is sending full RGB over HDMI. I believe by default it assumes that an HDMI connection is going to a TV, so it doesn't send the same color data it would send over DVI to a PC monitor. I don't have my system in front of me right now to find the setting though (currently on a laptop), perhaps someone else could chime in as to the location.

Interesting. I actually just switched "digital color format" in the NV control panel from RGB to YCbCr444 and it completely fixed the brightness/contrast issue I was having.

 

[Tobit]

I believe the first problem (only one DVI output working at a time) is something in all 970s - I seem to recall reading somewhere that it's set up to allow use of only one at a time, but can't find a link about it now.

and sorry to triple post but I was just looking at the box again. The box says I can drive up to four monitors using 1xDVI-I, 1xDVI-D, 1xHDMI, and 1xDP. I'm really thinking I either don't have the proper monitors and/or the proper DVI cables.

Both monitors, however, worked great together on both DVI ports on the GTX-260. Comparing the cables now, one was a single link and one was a dual link, both were DVI-D.