One GPU per display, any gains?

[flat tire]

I run 3 1440p screens. Each screen has its own instance of X-Plane 10, running windowed. X-Plane 10 is a flight simulator and each of the 3 copies / screens provides 58* of view. The sim does not support crossfire / SLI. I'm currently NOT running surround, because my GTX 770 4GB only has 2x DVI + HDMI + DP and I have to use the 2 DVI connectors, plus HDMI which has different timing. The DP as you may know doesn't work properly so I don't use it.

So, my question is, if I get another identical card or two, will they work to render the contents of their individual displays? Or will they just serve as outputs, with 1 GPU doing all the heavy lifting? Each program is windowed on its own screen. The reason I want another GPU is because the sim has already maxed out my 1 card according to GPU-Z.

TLDR: If I add more GPUs NOT in SLI, does each card do the work for its own monitor or am I stuck with 1 GPU doing all the rendering?

 

[cortexodus]

I think more information is needed. What is your platform? (CPU, mobo, PSU, RAM, etc.)

Based on what you're describing, I think it's possible that adding another GPU to drive say, the two outer 58° screens, may help by reducing GPU load on GPU0 by pushing that load unto GPU1. As it is, you're definitely cranking hard on that single GPU. However, I think X-plane does some pretty serious simulation on the CPU as well. If your CPU is the bottleneck, another card isn't going to help.

Also, is it not possible to have that application run fullscreen across the 7680x1440 resolution instead of using separate windows?

 

[flat tire]

I have a 4770K @ 4.5 + 16GB DDR3 1800 11/11/11/29 + ASRock Extreme4 Z87. I know my RAM is a little slow. One large window is not workable because the sim renders the view in one plane, and it's heavily distorted. In order to get a proper, minimally distorted wraparound 174* view I must have each 58* view rendered in its own plane. This requires one copy of the sim to run for each view.

 

[cortexodus]

I have a 4770K @ 4.5 + 16GB DDR3 1800 11/11/11/29 + ASRock Extreme4 Z87. I know my RAM is a little slow. One large window is not workable because the sim renders the view in one plane, and it's heavily distorted. In order to get a proper, minimally distorted wraparound 174* view I must have each 58* view rendered in its own plane. This requires one copy of the sim to run for each view.

I wouldn't worry about the RAM. It's hardly a limiting factor in that configuration. Seems to me that you've got a configuration that's got a lot of horsepower. But, honestly, I think the issue is effectively insurmountable in the configuration you're describing since you're not really running X-Plane, you're running X-Plane times 3 on the same box, tripling the work that the computer is doing I believe that type of configuration is generally achieved with multiple physical systems that are networked.

 

[flat tire]

Yes, the developer intent is to have multiple systems networked, with one dedicated system for each display. This makes slightly less sense now that one computer can run at least two displays. I'm maxing my card out before my CPU. I have HT disabled and there is still CPU available. That's why I'm interested in learning if it's possible to offload each instance of X-Plane onto its own GPU, if each instance is on its own monitor.

 

[cortexodus]

I'm not certain if it's possible to entirely "offload" these additional instances to a secondary GPU, but I suspect an additional GPU would help if the GPU is really what's holding up the show. Seems to me if they're running on those heads, then it's no longer on the primary GPU to do all the work.

Any way you can get hold of another decent GPU just for testing purposes before shelling for something more? The other thing I would do is check this out.

I'm curious how this works out for you either way. Your "test environment" is a gaming scenario quite unlike anything I've thought about before.

 

[flat tire]

My rendering settings are pretty well optimized. Anyone know whether an additional card will help?

 

[zandor]

3 program instances and 3 screens? Sure, 3 cards will work in that setup. If you disable SLI and connect one screen to each card then the GPU attached to each screen will handle rendering for it.

As much as NV's requirement that screens be spread out for surround annoys me, it would work well for you if you decide to get more 770s. Plug one monitor into each screen. Disable SLI to run X-Plane or enable it to run some other game in surround or on a single screen. I'd stick with NVidia for this until AMD pulls their head out of their ass and gets rid of the what screen plugs in where restrictions. NV has the same sort of problem, but their restrictions just happen to line up with your configuration. Personally I like AMD's requirements better, but that's because I'd like to have all my screens on one card when I boot up Linux.

You don't have to match GPUs when you're going to run with SLI off. I'd try to get GPUs with the same core though, just so drivers don't become a headache. For a 770, that's a 640 or higher. If a 770 is enough to run 2 screens you might consider getting a weaker card for the third display. If you play other games I'd just stick with the 770s though. That way you can use SLI in games that support it. Set them up so surround works, then disable it for X-Plane.

 

[flat tire]

I got another 770 4GB. Haven't done enough testing yet but here's what I can tell so far:

--All textures, even running 3 copies of the sim, get stored on 1 card.

--The rendering for the sim is all done on one card. The second card stays downclocked and does nothing for the sim.