Dual DVI card only outputting to one port

#1
Issue:

Graphics card appears to be only outputting signal to DVI-D connection but not to DVI-I for dual DVI monitor setup. (see more info below)

Setup hardware:

Graphics card: EVGA GEFORCE GTX 950 SC 2GB - card has one DVI-I and one DVI-D connection
KVM Switch: Tripp-Lite 2 DVI port dual display B004-2DUA2-K (DVI-D cables)
Problem PC: Custom Built ASUS X99-E with Intel i7 (ibuypower.com)
PC is brand new, just installed Win 7 Pro today, did full suite of OS updates to date, installed MOBO drivers, installed newest NVIDIA drivers, etc etc

KVM switch works flawlessly without probs for the 2nd PC which has dual DVI working. Based on quick research it appears the DVI-D cables on the KVM switch should work also on the DVI-I connection on the graphics card (maybe I'm wrong?) A monitor only gets a signal when plugged into the DVI-D connection on the card (tried swapping cables one at a time)

I tried the NVIDIA control panel settings, the windows extend display settings, and so forth, and none of them allow me to pass signal to both monitors as I normally would (for example on my 2nd PC which is working great with this setup)

So I am 99% sure it is down to the GTX 950 only outputting signal to one of the connectors (the DVI-D) or maybe I am confused about how the signals work or the type of signals. I don't see why this is not working.

Is there a BIOS setting or other setting somewhere that would allow me to force the card to output signal to both connections? Any other suggestions on what the issue or fix might be?

All help greatly appreciated, this is massively frustrating and is yet another in a long line of PC issues I've been dealing with for months ongoing now.
 


#2
My question; why are you using the KVM switch? It's not necessary as you connect the monitors directly to the GPU.
 


Neemobeer

Windows Forum Team
Staff member
#3
I didn't see any of the 950s with 2 DVI ports, but they do have HDMI and display ports. It's possible both DVI ports won't work at the same time. Have you tried the other ports?
 


#4
My question; why are you using the KVM switch? It's not necessary as you connect the monitors directly to the GPU.
This is a dual PC setup. This new PC is just one of two PCs I am using with the same two monitors.
 


#5
This is the item I have: https://amzn.com/B01DOB6VTU

The box specifically says "supports up to four concurrent displays" so it should definitely be able to output to both DVI ports at the same time.
 


Neemobeer

Windows Forum Team
Staff member
#6
Try bypassing the KVM and see if that is working, if it isn't I'd say the port is likely bad.
 


#7
Try bypassing the KVM and see if that is working, if it isn't I'd say the port is likely bad.
Thanks, good call! I bypassed the KVM and now both monitors work! That's good to know, but bad because now I need to figure out why the KVM isn't working. Probably a cable problem or a defective KVM port. Will investigate further....

Thanks again
 


Neemobeer

Windows Forum Team
Staff member
#8
Could be, or the KVM itself can't handle all of them, are the resolutions higher on the computer where the port "doesn't work"? I would test the following.
  • Swap the inputs for both computers, if the problem goes to the original working computer, it's more likely the port
    • Now disconnect the originally NON-working computer and see if the other computer works, if it does the KVM can't handle the resolution
  • If swapping and the problem follows the non-working computer it could be the output cable
 


#9
Could be, or the KVM itself can't handle all of them, are the resolutions higher on the computer where the port "doesn't work"? I would test the following.
  • Swap the inputs for both computers, if the problem goes to the original working computer, it's more likely the port
    • Now disconnect the originally NON-working computer and see if the other computer works, if it does the KVM can't handle the resolution
  • If swapping and the problem follows the non-working computer it could be the output cable
Thanks again. I just swapped the cables and ports in all combinations and have narrowed it down. The issue has something to do with the fact that the two DVI ports on the graphics card are different types (One is DVI-D dual link, and the other is DVI-I dual link). The DVI-I port is definitely the troublemaker.

This doesn't make sense to me, because the KVM switch cables I am using are DVI-D dual link, which theoretically should work when connected to the DVI-I port on the graphics card.

I am contacting Tripp Lite to ask them if they know what is going on.

Thanks!
 


#10
Well after waiting a few days, Tripp Lite responded. I am not very happy with the "support" they gave. This is the only instruction they gave:

"Verify the output of the DVI-I port is digital and not selected for analog."

That tells me nothing. I have no idea how to do that. I've googled for I don't know how long and I am coming up with nothing but useless info about DVI vs VGA.

I tried looking in the NVIDIA control panel but I cannot find anything about changing the output of the DVI-I port to digital vs analog.

Super frustrating. Anyone know what to do based on Tripp Lite's suggestion?

EDIT - I have just contacted EVGA with this question as well...
 


Last edited:

Neemobeer

Windows Forum Team
Staff member
#11
You can tell by looking at the DVI cable you are using if the signal is analog. If you look at the larger horizontal flat pin, if there are two small pins above and below it then it is carrying an analog signal. If you just have the big flat horizontal pin then it's a digital signal only. What is the model on the KVM?
 


#12
You can tell by looking at the DVI cable you are using if the signal is analog. If you look at the larger horizontal flat pin, if there are two small pins above and below it then it is carrying an analog signal. If you just have the big flat horizontal pin then it's a digital signal only. What is the model on the KVM?
They were extremely unclear in their wording then, because I already knew about the cable types. EVGA support replied today and confirmed the same thing - the signal is automatically selected by the hardware depending on the cable that is used. I am using the DVI-D cable with the single flat pin, so it should be digital. Thus I'm back to square one, this issue makes absolutely no sense. All hardware is set up as it should be, yet somewhere there is something going haywire. I am totally stumped.

Maybe I should uninstall the video card drivers, reboot windows, then reinstall. Who knows!

edit - kvm switch is tripp lite B004-2DUA2-K (with all DVI-D cables)

my other computer's graphics card has both ports as DVI-I with DVI-D cables carrying the digital signal to the KVM switch and they are both working fine. This is insane.

I wonder if the KVM switch has defective software that cannot work with DVI-I and DVI-D ports at the same time despite the cables being correct. I don't know, it could be such a crazy thing.
 


#13
Can you post a few pictures of your actual setup and how everything is connected?
 


Neemobeer

Windows Forum Team
Staff member
#14
What's your refresh rate and resolution on each output on the computer that doesn't work?
 


#15
Thanks @Neemobeer for your continued help. I appreciate you taking the time to assist. And thanks @bassfisher6522 for trying to step in as well. That said, I cannot figure this issue out, Tripp Lite support sucks, EVGA support is awesome but they don't know why exactly it isn't working with the KVM switch, and forums have tried to help but it's not going anywhere.

Thus, I've finally decided to go the non-ideal route and try a Display Port to DVI adapter. I am not at all happy about doing this, but I just tested it and it works, so I'll just suck it up and move on.

Thanks guys
 


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