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asked by (22 points)

The computer has two graphics cards: a high-end and a low-end.  It also has multiple monitors, most connected to the high-end card, some to the low-end.  It runs Windows-10.

When starting XP-11, it seems that sometimes it uses only the low-end card and this happens when Windows has its main display set to a monitor on the low-end card.  If I switch the Windows main display to a monitor connected to the high-end card and restart XP-11, then it will use the high-end card.

I want to tell XP-11 to always use only the high-end card.  Can I do that, and if so how?

commented by (22 points)
So, the aeroclub's Open Day is now past, and was a huge success.  The simulator was fully booked.  That effort is why it took some time for me to report back here.

We got a good result in the way described below.  This may be well-known to many, sorry if I repeat something everyone knows.

(1) the computer has a single CPU with multiple cores and runs Windows 10

(2) there are two GPUs, an NVIDIA GeForce GTX1080 and a 1020.

(3) the framerate increased dramatically when more than one copy of XP11 was installed because then Windows assigned different CPU cores to each.

We now have 24fps on each of six screens, running three instances of XP11, one master and two slaves.

We have not tested sharing the data files (textures, scenery, plugins…) between the instances: each instance has everything in its own folder, which is a huge amount of duplication.  But it works.

1 Answer

0 votes
answered by (3.5k points)
Have you tried assigne X-plane to the High end GPU from the GPU settings themselves? Do not ask me the exact steps as I will not be able to describe them precisely, but this is just an idea.

This might help though :
commented by (22 points)

Thank you.

This may help indeed: it will make the default crxd independent of where I set the main display of Windows.  So that problem is then solved.

However, the actual problem is telling specifically XP11 which card to use: there are in total 6 monitors and I want to run 2 instances of XP11, one which uses one card for  4 monitors and the other which uses the second card for the remaining 2 monitors.  (Or in fact any combination, but that's irrelevant).

I can tell the instances which displays to use easily from the XP11 graphics settings, but I can't tell them which card they should use. And:  this does not depend on which card a display is physically connected to.  Displays seem to get their video signal from a card, but the card that does the actual rendering work may be different.

Following your suggestion would make both instances use the same card.

The card to be used is therefore a setting that I would expect to be connected to each instance of XP11 and not to the whole OS.

commented by (22 points)

Ah, just found this:

and the last paragraph on the first page mentions a possible solutuion.

I'll have to go try it, and will report here if it was successful.  Not before Tuesday.

commented by (10 points)
Did you find A solution?

Have A simulator setup

I want to run three monitors on one GPU for front view and two side wing view monitors on another GPU all on the same pc, whats the Best option for this ?
commented by (22 points)
Jonas: no I did not find a solution.

So my setup now is like this:

(1) I have an instance of X-Plane, actually a full copy, for each set of monitors.

(2) the front view monitors are hooked to the fast graphics card

(3) Windows is set up to use one of the front-view monitors as its main monitor

(4) X-Plane's main instance (started up first) will then use the fast card, because it gets that from WIndow's main monitor, and the other instances will run on the other graphics card.

This works satisfactorily.  We have tried to use aliases for the data folders, so that each X-Plane copy uses the same actual files.  This works but led to some hiccoughs, so we continued to use extra copies of the files too.  However, there have been some updates of both Windows and X-plane in the meantime, but I have not tried to use aliases again.

So, repeat, for your case:

(a) install X-Plane twice, and install the data files twice as well.  You now have two X-Plane folders, each with inside it the data files and the program.  This is very similar if not identical to setting up a copy on two different PCs.

(b) hook the three front monitors to the fast card and the two side ones to the other card; make sure Windows uses one of the front monitors as its main monitor.

(c) set up one copy of X-Plane to be the master and the second one to be additional display; assign the monitors accordingly, i.e. the front three to the master copy and the other to the second copy. You do that in X-Plane's graphics settings.

(d) start the master copy, wait until the master copy runs and you are in the plane's cockpit looking through all three front monitors.  Then start the second copy.  It may take a little while for the second copy to get all its instructions from the master, you will notice that after a while the views of the second copy should be coordinated with the front three.

Good luck.
commented by (10 points)
Thanks a lot for your detalied answer

My setup is for now;

i5 7600K oc to 4.9 GHz

16 gig  ram 3200mhz

Asus Strix gtx 1060 6gb

3 pc. 20” monitors (1680*1050) for front Wiev on the gtx 1060.

This is running Smooth with 25-35 frames.

I want to ADD two 19” monitors (1440*900) on another GPU for side view .

What are your recommandations for GPU ? Ram? Any other upgrades?

My aim is to build s cheap funtional similator so A 1080ti is not an option.

At the moment i am using another pc fir the two side wievs but i want it on the same pc, the pc i am using now is an i5 6500, gtx 670, 8gb ram.

Best regards

commented by (22 points)
My second GPU is a GTX1050 GeForce.  It runs independently from the main which is a 1070 (no cable between them).  I get 24fps on all 6 screens.  Motherboard is 3.8GHz.

It also depends on how much detail you put in the landscape, the number of other planes to be simulated at the same time etc.  We kept those things to a minimum.
commented by (10 points)
Ok, thanks

What about ram, Will it work with 16gb ram to run two instances of xp11? What about video ram is 2gb enough to run two monitors? Or do i need to go for 4gb?

Is your CPU an I5/i7?
commented by (22 points)
Unfortunately (for you) I'm more a Mac/Unix guy, so I can't answer those questions without going down to the basement, switching it all on and looking around in the Windows setttings/properties.  I'll do that this evening as I'm busy right now.  To run two instances you should probably go for as much ram as you can, but the video ram I think is unimportant as it's on the GPUs.  I'll tell you later.
commented by (22 points)
OK, I had a few minutes before lunch, so I went down…

CPU: i7-7700, 3.6GHz

32GB ram, Win10 64bit

SSD: 386GB used of 489GB; this is because there is a lot of Google Earth landscape and OpenStreetMap roads in addition to all the X-Plane stuff.  This makes it realistic (it covers only the area around Geneva airport, about 10º in all directions) but needs a lot of data files, and they are of course there three times.

Main GPU: Geforce GTX1080 (so I made a mistake, I thought it was a 1070; but it's not the latest 1080 model)

secondary: GTX1050.

Both cards have 24GB, of which 8 dedicated and 16 shared.

So that's quite a beast then.  I bought it in January 2017, it's a year old.  I went straight for the top, plus I got a stronger than normal power supply just in case I needed to put in a higher-end second GPU.  However, for all those items I relied on the salesman's judgements: I know nothing of how PCs are put together; all I knew was that I could not do it on a Mac because I needed 6 monitors and two GPUs.  The shop I bought it from specialises in gaming machines, and originally they made a mistake by ordering monitors that were far too expensive.  The Philips 1920x1080 are more than sufficient (240V5QDSB) and they were surprisingly cheap for their quality.

The rest turned out to be OK, though they too had not understood that although the GTX1080 has five video outputs, only 4 can be used at a time.  No other of their clients had ever used more than three.

Hope this helps.
commented by (10 points)
Ok, thanks.

So all you six monitors are Full HD 1080P?

Do you notice any reduction in frame rate on your main monitors when you fire op the second instance of XP og the GTX 1050 GPU? if so how much.

Is the second installation of XP11 a total mirror of the main XP installation, eg. all plugins as well? I have X enviro do i need that in both installations?

As i can see your system is top notch, and my system is more average, i gues i can try it out with my sons GTX670 before i make any suggestions and go shopping.

Best regards,

commented by (22 points)

Yes, all monitors are 1080P, and they cost only 128CHF each!  Plus, they have no buttons or lights on the front, so it's all very quiet.  Did you see a picture?

I have not really measured it, but yes there is probably a small reduction in fps when the second gpu/XP kick in. I'll tell you next time I look.  The final fps is OK for my usage, which is mainly flight preparation for single-engine planes and they don't do more than120kt.

It's not too good with many rendering features enabled. e.g. forget it if you switch on shadows of trees.  :-)  But I don't do that. After the aeroclub's Open Days were over, I have used it mainly to see what it looks like at airfields in the Alps, France and Switzerland, where I have not yet been.  Mountains are dangerous things.

As it stands now, the second and third XP11 are complete copies of everything.  We have experimented with aliases to the landscape files and that worked (and saved tons of GB of course).  But there were some unexpected crashes too.  Now, we don't know if those were because of file access conflicts, and we could not really reproduce them.  Then there were a few updates of both XP11 and W10, and really I have not had time to investigate this in depth.  Plus that my W10 knowledge is very limited.

I must say that I did spend a lot of money on the total, plus a lot of time building the supports etc.  The idea was to sell it afterwards.  I can't upload images, but you can look at

I put some photos and the table of costs etc.  (the costs are in CHF for the benefit of the club, but I live in France and "think" in EUR).

commented by (10 points)
Wow, looks amazing, great simulator.

You say three instances off xp11? I thought it was only two. Im cunfused.

Wich monitors are running wich instance off xp11 and wich gpu?

Tried just for fun to start two instances of xp11 On my pc to see memory consumption, but it faills When i start a flight an The second xp11, says something about udp ports, Can you help mee out what to do?
commented by (22 points)
Yes I have three: the master does the front two screens, the second one the two on the sides of that, and the third does only the extreme left and extreme right monitor.  The four front monitors are connected to the fast GPU.

So, if the monitors are numbered from 1 at the extreme left, to 6 at the extreme right, then 1 and 6 are on the secondayr GPU; 2,3,4 and 5 are on the main GPU.  The master XP-11 drives 3 and 4, which sit straight in front of the pilot; the second XP-11 drives 2 and 5 and the third one drives 1 and 6.

I'll look at my setup for the UPD ports, but will do that tomorrow.
commented by (10 points)
But why use three instances?

In my case, will two instances do? one for the three front views and one for the two side views, or is another configuration a better option?
commented by (22 points)
One was very slow, two was better and three got us up to 24fps.

In your case two will probably do.  I have no data for other configurations.  You could try one, then two, on the monitors as you propose.

What I really don't know is how XP-11 hands out the work to the different CPUs and GPUs.  There must be an algorithm, but it is probably divided between XP-11 and W10.  Probably XP-11 hands out parallel tasks and W10 allocates them to CPUs/GPUs, and GPUs also do some of the parallellism.  I don't know at all how it is done in its details.

Then there is file access.  Clearly any process that wants to write to a file cannot do so if another one is reading or writing to the same file.  For XP-11 the scenery and airport data are only read, but there can still be conflicts depending on how the file system works.  So it may all go smoothly because the CPU interlaces the processes and no-one accesses the same file at the same time, but with multiple cores I don't know how it works.  It may go smoothly until such rare time that two processes need data from the same disc block at the same time and one or both of them signals an error to W10 and W10 shuts them down, essentially an XP-11crash.

The crashes we observed when we shared the data files between the XP-11 copies (I'm carefully avoiding the word "instances" because that would mean there is only one XP-11 program file, but the CPUs execute two different threads through the same code) may have been due to a bug in XP-11 or a bug in W10, and maybe it's gone now.  You may have better luck installing one disc copy of XP-11, one copy of the scenery & data, but set it up so that W10 has two XP-11 processes running.

In addition, I don't know how to do that on W10, my friend helped with that.  My OS knowledge is limited: it dates back to the 1970s when I was writing OSs, and the principles have remained the same since the 1960s, but the complexity has risen and the different ways of doing it with multi-core CPUs is huge.  It's like I know the thermodynamics of internal combustion engines, but would be lost if you asked me to look at a modern car: Renaults are not the same as BMWs.
commented by (22 points)

OK, more about my settings:

(1) on the main copy, i.e. copy 1:


visual effects: low; texture quality: high; antialiasing: 4x; no shadows; world objects: low; reflection detail: minimal; draw parked aircraft.


no multiplayer machines

external visuals: 2 connections

IP address: (that is the local machine)

UDP ports: 49010 and 49020

99 transmissions per second (but I suppose this only has to be higher than the frame rate)

UDP port we receive on: 49000; we send on: 49001

(2) Other copies, copy 2 and 3:

antialiasing 2x; texture quality medium;

role: external visuals

monitors: full screen simulator (and you have to set the views of course)

UPD ports: receive 49020 (for copy 2) and 49010 (for copy 3)

send on 49021 (for copy 2) and 49011 (for copy 3)

(3) Launch copy 1 first, resume or select a flight, and wait until in the aircraft.  Then launch copies 2 and 3 with "Resume Flight".

So for you this is reduced to 2 copies instead of 3.

commented by (10 points)
I have now bought an gtx 1050ti 4b card and are Ready to try it out, hope that my 16 RAM Will be sufficient.

When instaling copies of xp11, i guess i could install one copy of xp11 and the just make an copy of that folder to get the two copies?
commented by (22 points)
OK, I'm curious to hear how well it goes with the 1050ti.

As to the copies of XP11:  I don't really remember how my friend did it, but looking in the logbook I found an entry from 2017-04-05 which says "Moved old XP-11 install directory, reinstalled XP-11.  I suppose it's just moving & renaming the directories for each install.  Try it.

However, make sure everything is identical in both directories.

Also: I noticed that if you assign functions to control buttons (buttons on the yoke or quadrant for example) you have to do them identically on all copies.  I had one button on the quadrant assigned to toggle full brakes.  But on the other copy it was zoom-in.  Thus when I pressed that button, the brakes were applied on the main copy but the second copy wanted to do a zoom-in: it started to do that, then the master copy told it again which visual position to assume, and so there was some sort of jitter on the screens of the second copy.

Good luck.
commented by (10 points)
edited by

First attempt:

Just two clarify, this i my setup for now.

Windows 10 pro 64 bit

XPlane 11.11

CPU: i5 7600K (OC 4.8 Ghz)

RAM: 16 GB 3200 Mhz

GPU 1: Asus ROG strix GTX1060 6GB ( connect to 3 * 1680*1050 monitors for front view)

GPU 2: Asus ROG strix GTX1050 ti 4GB ( connect to 2 * 1440*900 monitors for side/wing view)

Installed the new GTX 1050ti card and latest nvidia divers. all ok

Connected the two side monitor on the GTX1050ti, and configured them in windows 10. all ok

Took a copy of my exiting plane installation in another folder

started and configured first copy of plane.

must write the rest tomorrow...

Setup graphics settings (XP11 copy 1) to 3 front view monitors.


This machine role: Master

External visual (machine locked to ours) locked view.

IP: Port 49020


Recieve: 49000

Send: 49001

Setup graphics settings (XP11 copy 2) to 2 wind/side view monitors. 90 degres angled to front monitors.


This machine role: external visuals

External visual (machine locked to ours) locked view.

IP: Port 49020


Recieve: 49020

Send: 49011


Fire op the forst copy XP11, all good running fine on GPU0 (Gtx 1060) three monitors.

Fire up the second XP11, but also running fon GPU0 (Gtx 1060) two monitors.

Googled - and realized that i need to right click the second copy of XP11.exe to choose to run it on the secondary GPU (GTX1050ti), now i t running fine and framerate os ok, a small degradation of frame rate on the front monitors, but only a few fps.

It seems like all the all 4 CPU cores are running 100% continuos when running two copies of XP11.

Load numbers in task maneger for the GPU 0 = 60-80%  + GPU 1 = 40-60% load. So i guess i need a better eg. a CPU i7 with 8 threads? Can you measure CPU/GPU load on your setup.

But the is some problem, when i load the second copy and load a flight, an error message appears "IP address is wrong - No NIC with this IP address" this is the ip of my PC? I click ok, and its running fine afterworth? Have i setup something wrong?

Another issue is, when i fire up the second copy of XP11 the sound is doubled? Is this normal, i guess I just need to turn off sound in the second copy?

I am also strugling with an faulty displayport to VGA adaptor (all my monitor only have VGA), so one of my side monitors keeps disconnecting, so have just ordered a new apapter, but this was an old error i knew of.

Thanks, a lot for all your help so far, hope you will help me the rest of the way.
commented by (22 points)
OK, curious to hear the rest.

BTW, I may have explained this in another post, but you should set the direction of view of each monitor such that the images of two adjacent monitors do not follow but take into account the rims which cover an appreciable angle of view.  If that's not clear I'll send a drawing.
commented by (10 points)
I have my monitor geometri setup by trial and error, but If you Got an god Way to setup the monitor i am all ears, please send me What you have
commented by (10 points)

this is my setup by the way....

commented by (10 points)

here another close op...

commented by (22 points)
OK, looks great!

So actually you have 7 screens?

I see 5 for scenery and one in front for the instruments.  Then one to the left with a map, and one to the right with what looks like a Garmin 430?  Are they also handled by XP11?

I tought of putting the instruments on a screen, and actually tried it too, but I prefer physical buttons, so I invested in the instruments.  Expensive and not as complete unless one buys 10 or 11 of them.  I have only 4.

You seem to have some buttons on the right of the intruments screen, how do they work?

I'll send the diagram later.
commented by (10 points)
edited by

Ok, yes something is missing, here the complete setup;

Windows 10 pro 64 bit

XPlane 11.11

CPU: i5 7600K (OC 4.8 Ghz), RAM: 16 GB 3200 Mhz

GPU 1: Asus ROG strix GTX1060 6GB ( connect to 3 * 1680*1050 monitors for front view) + to the right in the panel - one 7" hdmi 2d display for XP11 Garmin 530 POP out window.

GPU 2: Asus ROG strix GTX1050 ti 4GB ( connect to 2 * 1440*900 monitors for side/wing view)

In the middle of the panel A Separate Acer all in one PC with 22" touch screen running my instruments in Air Manager 3.2.

To the left is an iPad, running various aviation apps.

I have an Arduino MEGA 2560 connected via the ArdSimX interface ( and made my own physical buttons/rotary encoders for the Garmin 530 and HDG bug, ALT, and nav instruments.


nearly forgot

Saitek Switch panel

Saitek Multipanel, autopilot 

Saitek Pro Pedals

Saitek Throtlle

CH products Yoke

so thats in all 6 displays connected to the main pc, separate PC with monitor rung the instruments, and ipads for maps etc...

commented by (22 points)

Ok, so about the viewing angles.  Sorry if you already know this, and sorry if I repeat myself.  This is for my set-up, but can be adapted:

view anglesThere are 6 monitors in the above configuration.  If we start at the left side, the straight left lateral rotation offset for that monitor is then -90º and that between monitors is 36º.  The lateral rotation offset is determined by the direction to the middle of the screen.  However, the screens have rims, and those should obstruct some of the view.  If the field of view is also set to 36º then the screen displays too much.  The field of view should be a little less.  Otherwise a strange effect is noticeable, like in the mountain that is split over two screens (with exaggeratedly large rims in the drawing):  what disappears on one screen pops up on the next immediately, it is never obscured by the rims.  How much smaller the field of view should be depends on the screen. With a little trigonometry it's easy to calculate, although one can also just use trial and error.  In my case the calculation comes to almost exactly 35º field of view.

Unless one corrects for this effect, the motion of the scenery may really look strange!

(note also that my setup has almost 216º total view, even though the total angle between screens is only 180º).

There are other effects to take into account, e.g. the fact that the pilot's head is not really at the centre but somewhat to the left, and the co-pilot's is somewhat to the right.  Correcting for that I do by placing the pilot's head more to the right in the plane using the keyboard's arrow keys, and then rotate the head a little with the hat-button on the yoke.  The runway centre line should look as if it goes straight ahead.  A slight side effect of these two adjustments is that the left and right wings are not at symmetric positions, but in reality they are not either.  It is of course impossible to get the views right for two people, so I opted for none because in most cases there are two people in the simulator.

commented by (22 points)
Ah, good!  The Arduino solution is perfect.  I also have an iPad with various apps to supplement the experience.  Your setup looks really cool.  And a touch screen probably helps with a lot of things.  Lots of PCs…

I'm not that ambitious though.  But good to know all this!  Thanks,

commented by (10 points)
edited by
I actually fornd that touch screen control didnt work for me, so i build sine buttons, and that works just perfect.

I would appreciate If you could measure CPU and GPU ultilisation when all all three xp11 instances. By using task maneger.

It Seem that my bottleneck is my CPU with my current graphics settings, CPU is maxed out all the time but there is headroom on both GPU’s, havent experiment with lowering graphics settings yet.

The error i was having with the wrong ip was from the xuipc plugin, i have now removed all plug-ins from the second copy.
commented by (22 points)
Touch screens don't work.  Period.

One needs real buttons.

I'll measure the CPU/GPU but not right now.
commented by (22 points)

So… to get to the GPU usage, I needed to upgrade W10 (again; it's just as bad as with macOS or Ubuntu; one spends one's life updating).  But:

number of XP-11CPUfpsGPU1080GPU1050

Somehow I forgot to note the fps when a single XP11 runs.

The anomaly is that the second GPU seems to work less with 3XP11s running than with 2. But it may simply be that I did not wait long enough for the figures to stabilise.

The numbers did not depend on whether I was standing still on the runway or doing aerobatics.  It seems the second GPU does not do much, the first one works, but the CPU is used flat out!

commented by (10 points)
Ok, thanks.

Look a lot like mine, but i have fiddled a little with nvidia settings, and have got some good figures now, seem to run better with lower CPU utilization, it dropped around 10-15%, I will write more about specifik settings later.
commented by (10 points)
edited by

OK, XP 11.11, really rocks now.

I am using the latest nvidia drivers 390.65. and all is done done with my i5 7600K OC 4.8 ghz ang 16 gb ram at 3200 mhz, so no need for extra ram or change CPU ;-)

I am using default scenery with no addons, 

XP11.11 graphic settings on both copys of XP 11 are like this.

Visual effects: High (HDR)

Textture Quality: Max (No compression)

Anti aliasing: 2*SSAA+FXAA

Number of world objects: one stop before high.

Refelction detail: all way down (cant see any reason to use it)

Draw shadow on scenery: off

Vsync: off

allow windshield effects. off (on makes no difference in fps)

I am not using any AI aircraft yet.

I now got 30 fps smooth and stable on both instances of xp11, yeah I am really running all 3+2 monitors + one 7" with garmin 530 pop out, this i really amazing on pretty high graphics settings.

Did the following. 

Open Nvidia control panel.

goto manage 3d settings

Global settings:

changed power managment mode to "prefer maximum performance.

Program settings:

( i have set the following on both XP11-1.exe + xp 11-2.exe)

open gl renderer: for XP11-1.exe (gtx 1060)  and for xp 11-2.exe (gtx 1050ti)

Tripple buffering: on

Vertical sync: adaptive (half refresh rate) = 30 fps.

this did the job, great improvement in fps and lower utilisation off the CPU... wow.

Utilisation on running both xp11 installations.

CPU = 80-90%

GTX 1060 = 70- 90%

GTX 1050ti = 40-60%

this is measured in flying around and over Copenhagen in Denmark  EKCH where i live.

Happy flying and many thanks to you Robert, your support was top dollar ;-)

commented by (22 points)
OK Jonas, thanks for those settings.  I'll follow up on that, but in a few days or os.

Weather has gotten better, so time for some real flying now.