In the beginning I had a mysterious "very low FPS performance" problem in FSX (it was always around 6-7/sec average) and I tried many things to solve it. 

I played very much with "fsx.cfg" file and other settings, I worked on BIOS and hardware configuration, drivers, CPU settings..etc. Finally I could not find even any little clue about the reason, and I could not be able to increase FPS even a little.

But after I attached a second NVidia card to the same system (which has lower capacity than my current card), I see with this card I can reach to 40/s FPS without making any special settings.

So I understood nothing was about "fsx.cfg" file or other setting or other hardware configuration. It was only about my display card!

My first display card was NVIDIA GeForce GTX 950
The second card I attached was NVIDIA GeForce GTX 580

Now I am connecting them to 2 monitors at the same time (one card connected to one monitor), and shifting FSX windows from one monitor to another.
When I move the FSX window to "GTX 580" monitor FPS is around 40/sec, but when I move the window inside other "GTX 950" monitor FPS is immediately decreasing under 10/sec. (by the way in this monitor always scenery spikes, flashes happen too)

I recorder this situation in a video
https://youtu.be/6vtVPtvdY4w


How this can be happen?
What can be wrong with the card GTX 950?


But I must say that my NVIDIA GeForce GTX 950 has no problem in other applications. It is running perfect... Problem is only related with FSX.
For example with the same card I can play Grand Thief Auto 5 very smooth at high performance levels.


So what can be the cause of this NVIDIA GeForce GTX 950 & FSX cannot match each other?
Very interesting ...

This is an easy one, FSX needs memory band width and memory interface width and for the 950 this is way to low for FSX ( 105 and 128 bit ) where as the 580 has 192 and 384 bit, a NVidia GTX...50 card is to low end for FSX unless it is a TI.

Herman

Swap the 950's and 580's PCI-E slots and repeat the experiment.

Leave the cables and monitors running to the same slots, not cards.

If the results are the same, Electricman is right.

N99WB

On 9/17/2017 at 2:24 PM, electricman said:

This is an easy one, FSX needs memory band width and memory interface width and for the 950 this is way to low for FSX ( 105 and 128 bit ) where as the 580 has 192 and 384 bit, a NVidia GTX...50 card is to low end for FSX unless it is a TI.

Herman

Thanks for explanation.. I was asking this question to many people in last days, no one could give a clear answer as you wrote..

My technical knowledge is not quite enough to understand all details, but as I understand from your answer, GTX 950 hardware's memory using structure is not suitable for high performance in FSX ...in simple words this card's hardware is not very suitable for FSX... am I right?

Yes that is about it, you have to look at this in the next way, the speed of the GPU or CPU is how fast the water of a river is running, the bandwidth is how big or small the river is from one bank to another and the memory interface width you could compare with the depth of the river and the river has a cover over it so it can't flood, if both these last ones ( the both width values ) are to small then the speed will not prevent the data from being choked in the GPU even if it is a much newer card, FSX feeds a lot more data to the GPU then any game out there.The least you want for FSX is a 254 bit, 180 plus card to have some good results.

Herman

Great explanation electricman, as I was thinking of moving to a NVidia GPU from a 7850, and I am glad of your help.  Good post damlays, many thanks.

7 hours ago, electricman said:

FSX feeds a lot more data to the GPU then any game out there.

FSX is one of the least GPU-intensive games out there. This is why even with a GTX760 I couldn't overwhelm my GPU even at 2560x1440.

Go fire up nVidia Inspector and watch the GPU and MCU loads in real time when running FSX. The GPU load is unlikely to exceed 50% and I'd be shocked if the MCU load exceeds 25%. Look at data. It gives much more reliable results. :)

Cheers!

5 hours ago, gliderdriver said:

Great explanation electricman, as I was thinking of moving to a NVidia GPU from a 7850, and I am glad of your help.  Good post damlays, many thanks.

Thanks to Herman..Until now many people (some of them are experts) tried to find a reason, but only Herman could bring a real and clear explanation about the reason.

 

16 minutes ago, Luke said:

FSX is one of the least GPU-intensive games out there. This is why even with a GTX760 I couldn't overwhelm my GPU even at 2560x1440.

Go fire up nVidia Inspector and watch the GPU and MCU loads in real time when running FSX. The GPU load is unlikely to exceed 50% and I'd be shocked if the MCU load exceeds 25%. Look at data. It gives much more reliable results. :)

Cheers!

Yes I read this sentence "FSX is one of the least GPU-intensive games out there. " in many places before. That's why I always concentrated on CPU related solutions in the beginning.

But everything I tried until now shows me that Herman's explanation can be the only right one.

 

When I watch with Nvidia Inspector I see GPU load is nearly always around 99%.

 

Actually some people are saying me "There are plenty of people who have run FSX quite well with x50 and x60 graphics cards - your poor performance is more likely based on something on your specific system ".

But I don't know. I saw that in my case,  GTX 950  gives me very bad performance, while other card is giving me very good performance in the same system.

.

 

10 minutes ago, damlays said:

Thanks to Herman..Until now many people (some of them are experts) tried to find a reason, but only Herman could bring a real and clear explanation about the reason.

He provided a clear and convincing explanation, except it was wrong. People are naturally inclined to believe comprehensive and understandable explanations even if they aren't correct.

 

11 minutes ago, damlays said:

But everything I tried until now shows me that Herman's explanation can be the only right one. When I watch with Nvidia Inspector I see GPU load is nearly always around 99%..

Yes, GPU load. If Herman was correct and the GPU was starved of memory bandwidth then you would see the MCU number at >95% and the GPU significantly below that. The rule of thumb is that whatever is at or near 100% is your bottleneck.

I'd be curious what NI says your clock/memory speeds are, and whether you have removed all references to the 580 and 950 in your FSX.CFG before you start it.

Cheers!

Luke

5 hours ago, Luke said:

He provided a clear and convincing explanation, except it was wrong. People are naturally inclined to believe comprehensive and understandable explanations even if they aren't correct.

So you are saying his explanation is not matching with the real situation which is happening...

I recorded the video for you to show Nvidia Inspector parameters at flight...

 

I am curious to hear your idea -if you have-about the reason of this situation with GTX 950 card.

For me I found out that CPU has the most impact on FSX/P3d performance.  My old system clocked in at 2.33 GHZ, my new system clocks in at 3.6 GHZ.   My average fps jumped from 30 to about 50, sometimes topping 70 in the flight levels.  Meanwhile my vid card, which has only 3GB Vram as opposed to my former systems 8GB Vram, is not taxed at all, has no blurries or popping textures.

 Now I don't know how much P3d's being 64 bit matters, I am sure it factors into my performance.  IMHO the best investment for these sims is the CPU, every CPU upgrade I have done has seen a corresponding increase in performance and smoothness.  Plus I am sure having a modern hard drive helps with texture loading.  For me a good benchmark has always been the Valley benchmark at UIEngine.  On my old system fps were 25, on my new system, 70.  If you haven't seen the graphics on that benchmark, go download it.  Every tree branch, every blade of grass is animated and moves according to wind strength.

John

6 hours ago, damlays said:

So you are saying his explanation is not matching with the real situation which is happening...

I recorded the video for yodea -if you have-about the reason of this situation with GTX 950 card.

GPU is at 99%, MCU is at 1-2%. You are NOT memory-limited.

How does the 580 do? What's your screen resolution?

Cheers!

Luke

7 hours ago, Luke said:

GPU is at 99%, MCU is at 1-2%. You are NOT memory-limited.

How does the 580 do? What's your screen resolution?

 

As you can see from video on Nvidia GTX 580 CPU Load is much more lower and FPS is much more higher, compared to GTX 950.

 

If it is not about memory, then what can be the reason of this big difference?

 

 

My monitor resolution is 1920 x 1080

FSX resolution is 1024x768

13 hours ago, Cactus521 said:

For me I found out that CPU has the most impact on FSX/P3d performance. 

In my case, I cannot explain the performance with CPU, or with other hardware configuration, or with settings of FSX..

Because both display cards are on same system, using same CPU, same system configuration, same FSX settings...one of them has terrible performance, while other has very acceptable performance...

 

I could not find any explanation about this difference yet ??

How about the driver? 355.82 is 2+ years old.

Cheers!