Two graphics cards, where do I plug the monitor?

[tricky]

I have a machine with a Quadro card in it. I am adding at GTX 980 too.

I assume I can get RT GPU to use only the GTX 980 and leave the Quadro card for the display/interface etc? To do this, where do I plug my monitor - in the GTX or in the Quadro?

I also want to make use of the GTX card in games. Does this mean I need the monitor cable plugged directly into the GTX rather than the Quadro?

[benb32]

You're going to want to plug the monitor into the quadro in max (and setup the GTX to be the only device used for RT). When playing games you'll need the monitor plugged into the GTX. Sounds like a bit of hassle - you might be able to make it a bit more convenient by using a KVM switch...

In terms of drivers things are a little less clear. Apparently (from other people's experiences with dual quadro and GTX) installing the geforce drivers at default will install the geforce version of PhysX. This causes problems with vray seeing the GTX for in process RT rendering (this is an nVidia issue and would be the case with any program using the GTX for compute, when it isn't the viewport graphics card). However, for your games having the geforce driver would be a good thing for game specific optimisations. The work around is to install the geforce drivers but do a custom install without PhysX - then install the quadro drives and include the quadro version of PhysX. It's a bit of hack and depending on how nVidia do their driver updates you might find yourself playing around with the driver installs. All the best Ben

[tricky]

Thanks Ben. My Dell monitor has a multitude of ports. I have plugged in the Quadro via the DVI and connected my GTX via the displayport. Shouldn't I be able to switch the source on my monitor and jump between GTX and Quadro?

(can you tell I'm new to this???)

[benb32]

No problem Richard , using the multiple ports on the monitor would be even better. If it is a hi dpi monitor you'll need to use either display port or DVI dual link to let each graphics card drive the monitor at 60Hz - HDMI 1.4a will be needed on the monitor if you will be using that. More interestingly with the quadro setup you can enable 10bit colour if you have a wide gamut monitor. Using a wide gamut and calibration will let you colour match and proof - won't help with Max as it's not colour aware, but will improve the VFB when you load the monitor's icc profile. Just remember, once you're done doing your post in photoshop/nuke/after effects, to save your image with sRGB colour space for your Associates to view the image on a standard monitor.

[tricky]

Right. I have just installed the extra GTX card. I have the Quadro connected via DVI-D and the GTX connected via display port to the same monitor. It isn't a hi-def (4k) display - its a U2711.

It seems I can now change input source from the monitor controls and jump between displays. The weird thing is that I can now have half a 'window' (like a browser window) on one input and half on the other. Does this mean that the Quadro is powering half and the GTX the other half??

[benb32]

Yes, it does.

[tricky]

Yes, it does.

I am not sure if I understand what is happening here.

If I have 3dsmax session running on the DVI connected monitor (this is the quadro) and I have the RT GPU set to only use the GTX card, the vfb warns me that I am using the same card to render as I am using for the UI (so the system will become sluggish).

However, I am running the nvidia GPU utilisation app and it tells me the gtx is flat out but the quadro isn't doing anything (I see spikes in the quadro when navigating windows etc).

[benb32]

Hi Richard, from your previous post you mentioned that the DVI input came from the quadro and display port coming from the GTX. When you are using MAX / RT you will want the monitor switched to the DVI only (make sure you don't have the dual input on the monitor from both cards). Then you want to use the GPU select tool or clselect utility to only use the GTX card. If you have set the geforce and quadro drivers up as below you will see both cards available in the GPU list for in-process rendering. If you only see the quadro card, most likely the PhysX from the geforce driver is interfering. If you don't want to change the quadro and GTX driver installations, your final option will be to run RT out of process, just as it used to pre version 3.30. Hope this explains it a bit better, all the best Ben

[benb32]

Sorry my bad, didn't read your post properly - was viewing on my phone

Have you tried unplugging the display port completly to absolutely confirm the GTX isn't being used? Other than the message from the VFB, does it seem to be working correctly?

[tricky]

Sorry my bad, didn't read your post properly - was viewing on my phone

Have you tried unplugging the display port completly to absolutely confirm the GTX isn't being used? Other than the message from the VFB, does it seem to be working correctly?

It seems to be working as expected apart from the VRay warning message. I need to do some further testing.

[benb32]

Could be you've found a bug... might be an idea to let Blago know.

[savage309]

It seems to be working as expected apart from the VRay warning message. I need to do some further testing.

Technically you have a monitor plugged into the GPU, but you are not using it. We can't know if the plugged monitor will be used or not and we always show the warning when there is a monitor plugged into the GPU.
Since your UI and everything is working just fine, you can safely ignore the warning.

[benb32]

You're right as always Blago thought Richard had unplugged the GTX for the tests.

[tricky]

Technically you have a monitor plugged into the GPU, but you are not using it. We can't know if the plugged monitor will be used or not and we always show the warning when there is a monitor plugged into the GPU.
Since your UI and everything is working just fine, you can safely ignore the warning.

Thankyou. I understand.

[tricky]

On a related note (though very much off topic as far as RT is concerned) I want to run Unreal and have just the GTX card used for that. Regardless of the monitor I place the app on, my machine only seems to use the Quadro card (which is rubbish for Unreal). Any ideas on this?