I have two GPU cards, both RX480. Each limited to 6 DisplayPort monitors (with use of MST)

I have my computer setup to run multiplayer LFS on the one machine.
And the intent was to run 6 monitors off of each graphics card, and even add in a 3rd graphics card to get a total of 18 players. However, the graphics cards are posing a problem.

Obviously I cannot crossfire the video cards, as that would disable the video ports.
I cannot change the adapter settings in LFS, as the only one that works for windowed mode is the primary.

I can start up LFS in full windowed mode on any monitor plugged into the main gpu at well over 100 FPS, with a full grid of AI. If I drag the LFS window over to a monitor plugged into the secondary GPU it only runs at about 40~50 FPS. I can even open up more LFS windows on more monitors plugged into the secondary GPU and they too only run at 40~50, and 100+ on the primary.
Even in various hardware monitor programs the 2nd gpu never maxes out at 100%.


I am wondering why it is doing this, and if it is possible to make the secondary gpu run LFS at full speed. I need to know if I have to dump this single PC idea, and go with multiple Mini PC.


Is this due to something in LFS? Is LFS only optimized to use the primary video card?
I am kind of hoping this is all it is and they can fix it in the future.

Is this due to the graphics cards themselves? or the way dual graphics works?
Is there a setting I am missing?!

Is this due to some typical Windows crap? Win 10 Pro

Is this due to the fact that I am using a Server mother board with 32 Cores of Opteron Processors?
Is my server board bottlenecking video? I have 3 full 16x slots.

Your video cards are weak. You are using a server CPU and mobo, neither of which are designed to game.

Also, I really hope you have a commercial license for LFS, as you can't just use your personal license to make money off renting it out for profit.

Good luck.

I am aware of the server components issue vs gaming, but the system I have is just as fast as some older gaming machines, as far as single core goes. Dual 16 Core 6386 SE, typically runs at about 3.5ghz

I have commercial, last year and this year, have not actually used it to make cash yet though. The forum does not have a Commercial Licensed status, or it would be there.

I just need to know WHY the primary GPU runs at 100%, and the secondary runs at 50%. I do not want to run into the same problem if I build a different PC.


In the last test, I ran a few monitors on the 2nd GPU only, and it was a light load on the 2nd GPU, but it was also loading the primary.

I am currently assuming it is just the way LFS or Windows handles the full screen windowed mode applications.


Currently thinking about using separate i3-6100T mini PC on each cockpit.

Quote from SimulatorRental.com :

Currently thinking about using separate i3-6100T mini PC on each cockpit.

Maybe thats easiest combo

Yea but now I have an expensive server to sell before I can pay for the smaller PCs...

It was so close to working, if only there was a single GPU that could do 12 or more monitors

Quote from SimulatorRental.com :

I just need to know WHY the primary GPU runs at 100%, and the secondary runs at 50%. I do not want to run into the same problem if I build a different PC.

Just because your components are of "server" grade doesn't mean it won't run games. The problem you're facing most likely has to do with the way rendering works. LFS runs on a primary GPU but you want to display it on a screen that is connected to a different GPU. This means that every frame rendered has to be copied over from the primary GPU to the GPU to which the screen is hooked up to. Such an operation is quite slow which probably explains the drop in performance.

It runs the few games I play just fine, although they are games most people do not play ... its interesting to see some games use 8 to 16 cores. The most graphic demanding game I play is PlanetSide 2, on maxed out ultra settings, on a 3440x1440 monitor, and I only get 40FPS. Which is not that big of a deal, the problem lies in the fact that everything is delayed... I get shot dead before I even see the bullets come out of the other guys gun. This, and the micro stutters in LFS, are whey I am about to try a mini pc, Lenovo Tiny M700 i3-6100T.

16 of those tiny computers would use up just about the same power as the server setup I had. And while it would be stuck with onboard graphics... I only need to run 1 instance of LFS, it should be enough. But I will see when I test it...

1display "CPU-GPU" vs power "duo GPU" 2 display