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chickster25

Inside PC limits but still dropping FPS

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Hi all

I have an interesting issue and I am not sure the reason why. I have a powerful PC and have MSFS set to ultra with a FPS limit of 30. I have an intel 11900K and a RTX 3090 with 32GB RAM. Both are set to overclock if required,

At busy airports such as Heathrow and over London, my FPS can some times drop briefly to below 20 and seems to take a while to get back to 30.

I put some monitoring on my GPU and CPU and neither go above 50% so it would appear I have lots of capacity there.

My SSD is hitting 100% occasionally and my RAM is at 50% with a few higher spikes.

I am wondering why I cannot maintain 30 FPS all the time, even in busy areas?

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24 minutes ago, chickster25 said:

I put some monitoring on my GPU and CPU and neither go above 50% so it would appear I have lots of capacity there.

Overall CPU utilization is a useless stat when assessing sim performance--it's the ute rate on the individual virtual processors that limits the sim's performance.  If you look at the individual vCPUs, especially on the core that runs the main thread, that's what matters most.  50% overall CPU utilization means that the average ute rate is 50% across *all* the vCPUs, including the lightly-tasked ones--it's quite common to have one or a few vCPUs maxxed-out while the others are relatively unloaded--those maxxed out virtual processors are the limfac.

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Posted (edited)

We've run into this with previous flightsims...  Even state of the art hardware can be brought to its knees by the efforts of some addon developers...  Only remedy is to turn down the settings a bit 🙂

It is not hard to imagine overloading a PC with ultra settings at busy airports... level of detail, traffic, just the sheer volume of data.. it is going to hit a bottleneck somewhere 😉

Edited by Bert Pieke

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5 hours ago, chickster25 said:

I am wondering why I cannot maintain 30 FPS all the time, even in busy areas?

Not sure where you are based, but the high temperatures in the southern UK in recent weeks have had a noticeable effect on my cpu temps, even with good cooling.  When you looked at cpu loading, did you check the temperatures. They have to go quite high to cause throttling, but high end systems in hot weather can soon get too warm when they are working hard.


John B

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Posted (edited)
7 hours ago, chickster25 said:

Hi all

I have an interesting issue and I am not sure the reason why. I have a powerful PC and have MSFS set to ultra with a FPS limit of 30. I have an intel 11900K and a RTX 3090 with 32GB RAM. Both are set to overclock if required,

At busy airports such as Heathrow and over London, my FPS can some times drop briefly to below 20 and seems to take a while to get back to 30.

I put some monitoring on my GPU and CPU and neither go above 50% so it would appear I have lots of capacity there.

My SSD is hitting 100% occasionally and my RAM is at 50% with a few higher spikes.

I am wondering why I cannot maintain 30 FPS all the time, even in busy areas?

You should be able to maintain 30 FPS all the time with some potential caveats. Before going further, what method are you using for limit frames to 30?  And, open Dev Mode's frame rate OSD and display a screen capture from the next time you are not maintaining that 30 FPS so we can see what is happening w/ the main thread in particular. 

Edited by Noel

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I am using MSFS setting to keep to 30fps although I wonder if I should use the nvidia control panel instead?

My GPU temps are under 80 C as I didn’t push the overclock too far due to temps and the fact that the GPU was only running at 40%. 
 

I am using the graphs in MSI Afterburner  

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ok, appears to be the main thread that is the bottleneck. I cannot upload an image here but it says "Limited by mainThread" PC D3D11

MainThread 34.3ms (in red)

 

I have an Alienware Aurora R12 and have already set the CPU to overclock to Level 2, which is the maximum within the BIOS.

Not sure if there is a way to overclock further or spread the load across other cores?

Unless DX12 can help?!!

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17 hours ago, chickster25 said:

Hi all

I have an interesting issue and I am not sure the reason why. I have a powerful PC and have MSFS set to ultra with a FPS limit of 30. I have an intel 11900K and a RTX 3090 with 32GB RAM. Both are set to overclock if required,

At busy airports such as Heathrow and over London, my FPS can some times drop briefly to below 20 and seems to take a while to get back to 30.

I put some monitoring on my GPU and CPU and neither go above 50% so it would appear I have lots of capacity there.

My SSD is hitting 100% occasionally and my RAM is at 50% with a few higher spikes.

I am wondering why I cannot maintain 30 FPS all the time, even in busy areas?

Why only 30fps limit? Try 60fps, I'm sure, that it will minimize fps dropping under 30fps.

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Posted (edited)
35 minutes ago, chickster25 said:

ok, appears to be the main thread that is the bottleneck. I cannot upload an image here but it says "Limited by mainThread" PC D3D11 MainThread 34.3ms (in red)
I have an Alienware Aurora R12 and have already set the CPU to overclock to Level 2, which is the maximum within the BIOS.
Not sure if there is a way to overclock further or spread the load across other cores?
Unless DX12 can help?!!

Unless there is no detected bottleneck and I don't think that the hardware has yet been invented that will run MSGS without one,
one or other of the CPU or GPU will always show as "limited by". It does not mean that either of them is a problem, it means that the frame rate
counter apparently does not have, or no one can reach, a point at which it displays "not limited by either CPU or GPU".
MSFS is not yet finished and if anything should be added to the in-game frame rate counter, it is "limited by the software".

Your system is massively powerful and if the frame rate occasionally drops you should not obsess over it.
I cannot imagine a scenario where overclocking a 3090 could possibly be necessary and for sure, MSFS is not very tolerant of overclocking any CPU.

I think you should
a) limit the frame rate to 30, which will remove any overheating issues, turn the frame rate counter off and enjoy the quality what you see on the screen, or
b) leave the frame rate counter on and instead reduce the game settings until you have achieved the numbers that you aspire to.
You will need to disregard the accompanying fall in the quality of the image and the brightly coloured and highly distracting box on the upper right-hand side of your game.
 

 

Edited by Reader

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Increase things that use GPU and reduce settings that use CPU main thread to try and get a better balance.

 

 

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Terrain Level of detail is a CPU killer, start there......


Thomas Derbyshire

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1 hour ago, chickster25 said:

ok, appears to be the main thread that is the bottleneck. I cannot upload an image here but it says "Limited by mainThread" PC D3D11

MainThread 34.3ms (in red)

 

I have an Alienware Aurora R12 and have already set the CPU to overclock to Level 2, which is the maximum within the BIOS.

Not sure if there is a way to overclock further or spread the load across other cores?

Unless DX12 can help?!!

I think this is something we all have to live with. I don't think this is something that overclocking will remedy. I'm still mainthread limited on ground at heavy airports with my 12900KF on all-core OC to 5.2GHz. 

I'm in the SU10 beta, and DX12 can certainly bring better multithreading (if Asobo manages to sort out the current issues). We just have to see how it is when SU10 goes live on Aug 23. 

The biggest influence on main thread is terrain LOD. So reducing that while at heavy airports should help. 


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Unless I've missed something, you haven't stated what:

1. Aircraft you are flying in the London area. 

2. Your LOD setting is. 

3. If any, AI you are using. 

I have a similar setup to yours apart from an RTX 3080Ti and I can confirm that all of the above are CPU dependent and will bottle neck if not set appropriately. 

If 1. is the Fenix A320, then you will have real CPU bottlenecks as its very CPU intensive. I have it, but prefer to fly the FBWA320 as it's far less dependent on the CPU (main thread around 6-8 msec quicker)  and with the fps externally limited to 32 in rtss, I have plenty of headroom and lower CPU and GPU temperatures ~65°C with some pretty high ambient temperatures here in the UK at the moment! 

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I tested with a PMDG 737 but also get issues with standard aircraft in high density areas.

LOD is 200

AI aircraft is 50%
 

I can change these but this is what I use for consistent tests

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I'd reduce that LOD to 100 then re-check the main thread and fps. 


i9-12900KF | Asus ROG Strix OC RTX 3090 24GB | G.Skill Trident Z5 32GB DDR5 | MSI MPG Z690 Carbon EK X | WD Black SN850 2TB | LG 77" OLED | Thrustmaster Hotas Warthog | MFG Crosswind pedals |

“Intensify the forward batteries. I don’t want anything to get through”

 

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