Main tripple screen plus 3x export to MFDs "issue"?!

Hi all,

I would like to bring something up I personally don´t really understand. But first I explain what hardware I’m using how.

I have 3 large screens (27”, 2560x1440 75Hz) for my cockpit and 3 small ones (8”, 1280x720, 60Hz) for my 3 Cougar MFDs. VSync is off.

I´m using a 1 screen monitor configuration which looks like this:

To let the 6 screen run I’m using my main GPU (1080Ti) for the 3 large screens and one small screen. For the other 2 small screens I´m using a GT 1030.

My configuration in DCS looks like this.

Now to my “issue”, which I actually wouldn´t call a problem, but what is wondering me. When I’m using the 3 main screens only, I´m having 52 FPS in an own created multiplayer mission (Hornet cockpit at Khasab AB in the Persian Gulf, hot machine). The resolution in the DCS settings is 7680x1440. So far so good.

When I now expand the rendering area to display the MFCDs/AMPCD on the 3 small screens this gives me a resolution of 10240x1440 (14.745.600 pixels). Now the strange thing. Even if I´m not exporting anything to the small screens (means the export isn’t configured in the monitor config lua) my FPS are already dropping to 35. The 3 small screens are black. If I´m now exporting the MFCDs/AMPCD, this has no further FPS impact. What is strange as well is the fact, that I´m getting the same low FPS when only using 2 small screens at a resolution of 8960x1440 (maybe 1 FPS difference, I use this for the A-10C)

When placing the small screens to the bottom of the 3 large ones, which has a larger overall amount of pixels (7680x2160 = 16.588.800 pixels, 12,5% higher compared to my original layout) this results into the same amount of 35 FPS.

Those are the facts. My idea now is, whenever the GT 1030 is used, the FPS are dropping. I used a GTX 1050Ti instead, but this didn´t show any difference.

Is this really related to the rendering area, means the black color is an overlay like the land covering the water?

Why isn´t there any difference by placing the small displays sideways and below the main screens?

Could the PCI-E port be a bottleneck, being crippled to 8x by using 2 GPUs?

Is there a Nvidia Control Panel setting I can use to boost something?

I’ve updated the main GPU from a 1070 to a 1080Ti some time ago, which showed a 25% FPS boost with the same settings and hardware. Still the GPU is at 98/99% as it was before.

I know this is a long thread and my “issue” is kind of special but maybe somebody has an idea which can help me.

Thanks in advance and have a great day,

Xoxen

OK, checked the internet for an additional time now but didn´t find too much about this. I guess it is like it is, but what I will try is the usage of a Matrox Triplehead2Go. This would make it possible to combine my 3 small displays to one wide display and run all of them on the GTX1080Ti only.

The GT 1030 has a load of appr 65% when running the game, so it does anything.This "anything" could lead as kind of a break to my system. Once I can get a cheap TH2G and I´m able to try this I will share.

For any other comments I´m more than willing to listen to them.

Thanks,

Xoxen

So I would imagine its a driver issue. Nvidia not optimized to support the spread of multiple monitors over 2 cards. I really don't think its a bottleneck to the PCI-e at 8X. I don't know about RTX bandwidth on the PCI-e bus but prior to that I heard on many occasion that pci-e was never fully saturated with previous Nvidia cards.

Question have you ran a graphic card monitor program like MSI afterburner to see how much Vram is being used? Maybe the card is tapped out.

.....

Question have you ran a graphic card monitor program like MSI afterburner to see how much Vram is being used? Maybe the card is tapped out.

Thanks Brewnix,

I checked this with MSI Afterburner and in the following you find what it does at my test mission (there it shows 36FPS, but it always jumps between 35 and 36 being mostly on 35 ;) )

Sometimes the RAM of the card is fully used, mostly in larger MP missions. But as my test mission used appr. 7-9GB of RAM, I would exclude this to be the problem. I hope I´m right with this thinking.

Regarding the driver issue this would be something I also could imagine and which would make sense to me.

Thanks again for the input.

Xoxen

OK, I have great news. I bought a used TripleHead2Go and now I have connected all 6 displays to the GTX 1080 Ti. Everything works like charm. Immidiately I checked my test mission and wow, I have the full 53 FPS I also have without the exports. Not even a single FPS less.

Conclusion 1: Best investment ever!

Conclusion 2: 2 Graphic cards (Nvidia in my case) work together, but they caused a massive FPS loss in my case. As I checked a GTX 1050 Ti as well I doubt it was the weakness of the GT 1030.

Anyway, I hope this helps others as it helped me to save 1000,- EUR by buying a new CPU, Mobo and RAM. This costed me 100,- EUR (and an additional 100,- EUR for a faulty TripleHead2Go, I´m still fighting with the seller to get my money back).

Conclusion 3: I´m so happy :thumbup:

Unfortunalely I meet with friends tonight and tomorrow night, no flying time.

You've probably already figured this out, but the problem is that DCS only has one render surface, but the output is split across two GPUs. The rendering is done on only one GPU (the 1080 Ti), but part of the output image needs to be copied to the other GPU (the 1050Ti) in order for it to display. There's no direct connection from one GPU to another, so it needs to be routed through the CPU. This is why you don't see any difference between the 1050Ti and 1030; the CPU is bottlenecking how fast data can be copied from one GPU and pasted to the other.

By using the TripleHead2Go, this keeps the output on just one GPU, and this overhead is avoided. Incidentally, this is also why the SLI bridge was invented, to allow two GPUs to directly communicate with each other without the overhead of having to go through the CPU.

Do i understand this correctly? With a triplehead2go you can get 6 screens from one card?

3 connected to the card directly and 3 others connected through the triplehead2go on a fourth port on the graphics card using only for ports in total?

That would solve all of my problems.

You've probably already figured this out......

This makes perfect sense. As mentioned I was short before buying a new CPU and I strongly believe that this would have imroved my FPS and I would still have a bottleneck with the two cards. I´m glad I found the cause before that :smilewink:

Do i understand this correctly? With a triplehead2go you can get 6 screens from one card?.......

This is exactly what it does. There are several versions of the TH2G out there, I have the "Digital SE" one which uses the Display Port of the graphics card and has 3x DVI for my displays. Now I can rund all 6 displays at one Nvidia card. If this is your problem you can solve it with the TH2G.

Cool!

Thats solves my problem with running separate MFCD's and RWR

I had similar problem recently especially because I'm using AMD 5800X3D that doen't have integrated graphics.

My main GPU is RTX4090. When I installed a second NVidia GPU I had FPS issues. Then I tried RXT4090 togheter with an AMD Graphic Card and now it works flawlessly

Thanks for sharing, even though this wonders me. I had some strange experience with an Nvidia GPU and the onboard Intel graphics. It worked for a time but with an Intel driver update I had similar experience like described in the first post in this thread.

In the meantime I switched to a 49" display, have less fisheye at the edges because of the lower resolution and still run my 3 small displays via the TH2G from Matrix. I wonder if it still rund under Windows 11.....