How to debug why 3rd DVI monitor isn't working

3

Here is my video card Sapphire HD 6850 PCIE Video Card (100315L)

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Using the 2 DVI outputs on the video card and one the motherboard, I tried to connect 3 monitors to my Windows 7 PC, but the 3rd one is always coming up blank.

How do I begin to troubleshoot whatever is wrong here?

Raj More

Posted 2011-10-22T23:59:14.720

Reputation: 831

1In your Device Manager, do you see both the ATI and IG listed and are both working properly? If not then you may want to upgrade your BIOS/check your BIOS. If you do see them, then go into your Windows Monitor/Resolution changer thingy and see if the third monitor is displayed there. Is there a reason why you're not using the Display Port on the ATI. This card does support 3 monitors (i know cause i'm using the same thing) – kobaltz – 2011-10-23T02:04:22.453

Answers

2

It should work on Windows 7. Multiple monitors controlled by different drivers is officially supported.

Does each port work by itself? If the motherboard port doesn't work under any circumstances, the most likely issue is that the port is disabled in the BIOS. You'll need to enable it in the BIOS and make sure it has a driver installed.

You'll be a lot happier, and get much better performance, if you get an HDMI-to-DVI adapter and connect all three monitors to your video card.

David Schwartz

Posted 2011-10-22T23:59:14.720

Reputation: 58 310

I do have it enabled in the BIOS. I am now checking for drivers. – Raj More – 2011-10-23T00:21:40.113

There were two settings in the BIOS for this. I had to set both, and set up the driver. Works like a charm now. – Raj More – 2011-10-23T05:05:43.027

0

Many motherboards don't allow both integrated (on-board) and discrete (card) video controllers to be used at the same time.

You may want to check the support resources from your motherboard's manufacturer to confirm or deny this ability with your specific model.

Ƭᴇcʜιᴇ007

Posted 2011-10-22T23:59:14.720

Reputation: 103 763

This really is not true. I have yet to come across a PCI-E 16x mobo with integrated graphics that would not allow both onboard graphics and PCIE graphics to be enabled at the same time. I've set up several 3+ monitor setups like this and never had an issue. – kobaltz – 2011-10-23T02:01:58.307

Trust me, plenty of PCIe boards don't allow this. The current generation do for the most part, but most before did not allow this. For example, the entire Intel 3 series, and 4 series boards/chipsets. See Running Intel 3000 HD and a Discrete Graphics Card at the same time and/or How can I enable onboard graphics AND dedicated card simultaneously? for more info.

– Ƭᴇcʜιᴇ007 – 2011-10-23T02:21:15.823

0

HDMI to DVI uses a passive adapter or cable. Use such an adapter or cable to connect the third DVI monitor to the HDMI port on the graphics card. As already mentioned the integrated graphics is often disabled when you use a discrete graphics card.

Brian

Posted 2011-10-22T23:59:14.720

Reputation: 8 439