Multi-GPU for Multi-Screen Gaming?

[RobFRaschke]

If you guys can check my thinking on this, or if you have some experience, all the better!

 

I can't do VR, it makes me sick and gives me a headache, so that is unfortunately not an option. As such, and wanting a more immersive experience I game on multiple monitors regularly. I play a few games here and there, but it seems AAA titles just don't benefit from it, so I'll be concentrating on Elite Dangerous, EVE(less so, haven't tried it yet if so, probably mutliple accounts in multiple windows), Forza Motorsport 7 and Forza Horizon 3. I also have a bad tendancy to multi-task inappropriately, but things along the line of Hearthstone, youtube and forums up on separate screens at the same time. Yes, I have lost games because I wasn't paying enough attention to hearthstone. I will be getting new monitor(s) and video card(s). I'm leaning away from a 35" Ultrawide so that AAA titles and FPS games don't have to be driven on that full resolution, or have black bars that are just a waste of monitor real estate, but it's an option. I'm leaning in the direction of three 24" screens, with the primary monitor being a high refresh rate screen, and the two side screens just being 60 or 75hz screens. I believe Asus has some closely matching screens with differing refresh rates(?) that would be interesting.

 

So where I'm unsure on function would be between one higher end video card, like a 1070ti for all three, or getting two separate cards, like a 1060 6gb for the primary where I'll run AAA titles, and either a second 1060 6gb, or a 1050ti to run the secondary monitors because they're less likely to be as busy, etc. They won't be SLI because it's multiple screens, however I do have an x470 board, because B450 is just out, and I built this system a couple weeks ago. Current CPU is a Ryzen 5 2400g which should be sufficient, running all 4 cores at 4.0ghz when I scale back the iGPU, or at 3.75ghz with the iGPU at 1450ish. If I can shut down the iGPU with a dGPU, I'm comfortably that I can hit 4.1ghz on all cores, and run cooler in the mean time. If I need to step up to a 2600 or 2700 later if it's truly necessary, or maybe pick up a 1700 on a deal as they're getting cheaper, but I'd like to not have to. I know I only have 8x PCIe lanes on the CPU for the primary, and can use the chipset for the secondary, which is less than ideal, but given the hardware I'm thinking about using, I don't necessarily think it'll be an issue.

 

Have you tried this? Something Similar? Did it work? Do you know from other experience of issues in a set-up like this? Any thoughts on the games listed functioning with the card(s) listed? Am I just trying to re-invent the wheel?

[Stefan Payne]

9 minutes ago, RobFRaschke said:

r getting two separate cards, like a 1060 6gb for the primary where I'll run AAA titles, and either a second 1060 6gb, or a 1050ti to run the secondary monitors because they're less likely to be as busy, etc.

Doesn't work that way with Windows.

 

ONly the Primary card does the Work, the others are just dumb 2D Graphics cards. It wouldn't matter if you'd use a G450 (or G550) PCie for the second and third screen.

 

So only the primary graphics card does any work, all others are just display outputs.

[RobFRaschke]

Just now, Stefan Payne said:

Doesn't work that way with Windows.

 

ONly the Primary card does the Work, the others are just dumb 2D Graphics cards. It wouldn't matter if you'd use a G450 (or G550) PCie for the second and third screen.

 

So only the primary graphics card does any work, all others are just display outputs.

Even if the monitors are directly attached to the secondary card? The card would be doing the 3D processing for the attached monitor, would it not?

[Stefan Payne]

Just now, RobFRaschke said:

Even if the monitors are directly attached to the secondary card? The card would be doing the 3D processing for the attached monitor, would it not?

No, it would not in Windows 7 and later (Vista did not Support multiple Graphics cards or multiple Drivers I forgot).

I think what you described might have been the case in earlier WIndows versions like 95, maybe 2k/XP. But I've never tried it, so I can't say.

 

But since Windows 7 you only have one device that does all the Work and everything else is just a Display output...

And that was what I tried...

[RobFRaschke]

10 minutes ago, Stefan Payne said:

No, it would not in Windows 7 and later (Vista did not Support multiple Graphics cards or multiple Drivers I forgot).

I think what you described might have been the case in earlier WIndows versions like 95, maybe 2k/XP. But I've never tried it, so I can't say.

 

But since Windows 7 you only have one device that does all the Work and everything else is just a Display output...

And that was what I tried...

This is why I hate windows sometimes. SLI/Crossfire is BS, so that's a vote in the direction of 1070ti? Or is it likely that's underpowered for triple 1080p screens, just over 6 million pixels? It's about 25% less pixels total than 4K.

[samcool55]

10 minutes ago, Stefan Payne said:

No, it would not in Windows 7 and later (Vista did not Support multiple Graphics cards or multiple Drivers I forgot).

I think what you described might have been the case in earlier WIndows versions like 95, maybe 2k/XP. But I've never tried it, so I can't say.

 

But since Windows 7 you only have one device that does all the Work and everything else is just a Display output...

And that was what I tried...

Wait wut? That's not exactly what my experience is.

 

I have a multi-gpu setup and multi-monitor.

1 monitor (main one) is connected to my rx 480, other monitor is connected to the iGPU.

If i play a video on my main monitor, the rx 480 gets a load, if i move it to the other monitor, the iGPU takes over.

The load changes if the majority of the window changes monitor.

So, if 60% is on the main monitor and the other 40% on the iGPU monitor, the rx 480 gets the load.
If i switch that around, (60% iGPU and 40% rx 480) the iGPU takes over.
I can also see the transition happen because it freezes for like half a second.

Personally i would go for the triple monitor with high refreshrate monitor in the middle. That's what i have. Doesn't require an insane graphics card, no problem with game support because it's a common resolution and the extra fps will be used.

Get the most expensive gpu you can get, use that for the main monitor and connect the other ones to the iGPU.

[RobFRaschke]

19 minutes ago, samcool55 said:

Wait wut?

-Snip-

Well Bollocks. Which is it guys?

[O9B0666]

37 minutes ago, samcool55 said:

Get the most expensive gpu you can get, use that for the main monitor and connect the other ones to the iGPU.

Do this 

[RobFRaschke]

I'm mildly concerned about that many pixels on the iGPU in gaming that's stretched across all three monitors, I.E. using as a 5760x1080 in in forza and Elite Dangerous, it's not main line of sight in the games, but the added peripheral vision in those games specifically is massively helpful and good for immersion. 

[Stefan Payne]

2 hours ago, samcool55 said:

If i play a video on my main monitor, the rx 480 gets a load, if i move it to the other monitor, the iGPU takes over.

See, here lies the Problem.

YOU are Talking about Video.

I am talking about 3D applications. 

See the Problem?

 

And what Windows Version are you talking about? 2000? XP??

1 hour ago, RobFRaschke said:

Which is it guys?

With 3D Applications the Primary does all the Work.

With GP-GPU, the Primary does all the Work.

Unless the Application doesn't specify it otherwise (wich isn't implemented in most cases).

 

 

And that was my experiences with an AMD Kaveri APU and an AMD Graphics card. The AMD Graphics card switches itself completely off when the Screen goes dark, wich caused the APU to take over...

 

And I've also tried it with two 7970GHz/280X and an 8800GTX. THere was no way I could get some load on the nVidia Card...

 

[Froody129]

2 hours ago, RobFRaschke said:

Well Bollocks. Which is it guys?

As @Stefan Payne said, you can only have one primary card that is doing the work for 3D applications. When you are running the desktop then the card that the monitor is connected to will do the work, but when it is a full screen app like a game then you can't use other cards to offset the load unless it's SLI. For triple 1080p I'd go like 1080/1070ti or a used 980ti/1070 if you're on a budget.

[samcool55]

3 hours ago, Stefan Payne said:

See, here lies the Problem.

YOU are Talking about Video.

I am talking about 3D applications. 

See the Problem?

 

And what Windows Version are you talking about? 2000? XP??

With 3D Applications the Primary does all the Work.

With GP-GPU, the Primary does all the Work.

Unless the Application doesn't specify it otherwise (wich isn't implemented in most cases).

 

 

And that was my experiences with an AMD Kaveri APU and an AMD Graphics card. The AMD Graphics card switches itself completely off when the Screen goes dark, wich caused the APU to take over...

 

And I've also tried it with two 7970GHz/280X and an 8800GTX. THere was no way I could get some load on the nVidia Card...

 

Im using Windows 7 and a mix of an intel iGPU (did it on an i5 4690k) and an rx 480.

With games the main load is handled by the card that has the main display connected to it (can be changed in windows).
If you either change the main display or change for the specific application what GPU you want it to use, you can change where the load is. You can perfectly run 1 3D application on the main gpu and another one on another GPU as long as the 3D application allows you to tell it which GPU it needs to use. In most scenario's however the option won't be there but there are situations where you can have multiple 3D applications running on different GPU's.

 

But the thing is, if you have 3 monitors connected to the PC, (center one to graphics card and the rest to the other monitors) you don't have a surround setup, you have a multi-monitor setup, not the same thing.

 

If you have a multi-monitor setup you aren't suppose to game on it like a surround setup because that's not how it should be used.

Multi-monitor = multiple displays which are handled separately.

Surround = multiple displays combined to create 1 big display and are treated as 1 big monitor.

In a multi-monitor setup, you can like run the game in windowed on the main monitor and stretch it while running over to the other displays but that completely ruins performance because the main gpu needs to render the image and move part of it to the other GPU which is REALLY slow.

 

Anyway, back to the question.

If you run a 3D application by default it will run on the main monitor. Unless you tell the application specifically which GPU to use. If you move the 3D application while it is running between monitors, the load will stay on the same GPU but it will take a big performance hit because all the rendered frames need to swap GPU first before they can be send to the display.

 

Video's can change GPU's in real-time. You move the window, the right gpu takes over.

You can use SLI or crossfire to combine multiple gpu's that are compatible with each other to use multiple gpu's for the same 3D application. However i don't recommend it because support is really bad these days.

 

If you want to run your game spread over multiple monitors (a surround setup) you will need to connect all the monitors to the main GPU.

 

If you are wondering why it's a good idea to use your main gpu ONLY for the main monitor you will use for gaming and a different gpu for the other monitors you won't use for gaming (basically a multi-monitor setup). it's mainly a performance thing. If your main gpu needs to take care of all monitors, your performance will be lower because your main gpu will not only render your game but also whatever is on the other monitors. If you split the load and connect the main monitor only to the main gpu and the other monitors to the other gpu, your performance will increase because it doesn't matter at that point what's displayed on the other monitors. The main GPU doesn't care and can focus on the game. (there is still a possible cpu hit but that's the case in all scenario's and nothing you can do about).

[RobFRaschke]

Ok, that does answer my question, and in the cold light of day, makes perfect sense. I have some odd ideas about the way I'd like things to work in the wee hours of the morning, which is why I like to double check.

 

Thanks for your help on this guys.

[Mick Naughty]

I always use multiple cards for surround gaming. Assuming that’s what you mean compared to just gaming and having other monitors. I use my igpu as well. So 4 monitors on one rig and 2 on the other. 

[RobFRaschke]

21 hours ago, Mick Naughty said:

I always use multiple cards for surround gaming. Assuming that’s what you mean compared to just gaming and having other monitors. I use my igpu as well. So 4 monitors on one rig and 2 on the other. 

Have you actually monitored GPU usage on the cards to confirm distributed load?

[Mick Naughty]

6 hours ago, RobFRaschke said:

Have you actually monitored GPU usage on the cards to confirm distributed load?

During what exactly?

[RobFRaschke]

On 7/28/2018 at 7:17 AM, Mick Naughty said:

During what exactly?

During Gaming.

[Mick Naughty]

6 hours ago, RobFRaschke said:

During Gaming.

If you mean surround gaming, the load isnt distributed, it’s the same as sli at that point. The cards are still maxed out as they should be usage wise.