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Scotster

Sudden low utilisation of GPU

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All of a sudden I have a strange issue with FSX. I'm still managing reasonable frame rates but nothing like I was previously. I'm not really sure what's changed but I am using Windows 10 which updates itself a LOT and I have also installed a few other games that may or may not be having an effect. The trouble is that I feel like I may be looking for a needle in a haystack.

 

Previously I was using approx. 60-80% of my GPU and the frame rates were through the roof. Now I'm using a maximum of 36% and the frame rates are much lower than they were previously. I have not changed any CFG files at all, in fact I actually restored a backup I had just to make sure. CPU usage is exactly like it's always been, approx. 100% across 3 cores and around 90-100% on one core.

 

Has anyone came across anything like this before? Just looking for some pointers before I go to town with my install.

 

Thanks

Scott

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Has the problem started since you installed the other games? If so, try uninstalling them and see if the problem persists.

 

Have you blocked driver updates in Windows 10? If not, it's possible that a new graphics driver may have been installed. Other updates are less likely to affect graphics performance - if they did, every gamer would be complaining!

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Hi there,

 

I'm not entirely sure when it actually happened. I only noticed during a bit of testing. When I first started out I worked like crazy to get everything set up perfect, once it was I backed everything up. From there I've installed Steam, installed games, they in turn have installed updates, etc, etc, etc.

 

I took everything out but it made no difference. I then completely wiped my PC and started from scratch. I still can't get it to work the way it was previously. It's very strange, I must have completely fluked upon the setup and now I can't replicate it :(

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What CPU and graphics card are you using? What CPU temperature are you getting when running FSX? If the temperature is high the CPU may be throttling and reducing the FPS as a consequence. Also, if the CPU is running mostly at 100% it may be creating a bottleneck for your graphics card, hence the low GPU usage (although not sure why this has only just started happening).

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CPU is an i7 6700k overclocked to 4.2Ghz. GPU is a GTX1080 running stock clocks. Memory is 16GB DDR4 RAM. FSX is installed on it's own SSD drive with all the addon's and updates etc.

 

CPU temps are approx. 70C (it's a laptop) at full load, no throttling to note. All 4 cores of the CPU will run between 90 and 100% during a flight. GPU temps are rock solid 49°C as it's barely being used.

 

I had a bit of a play around today. I started messing with the bufferpools figures. My smoothest and best performance always came from Usepools=0 but now I'm seeing the best results with Usepools=1 with a PoolSize=120000000 (I think, might be +/- a zero or 2). I messed around with LOADS of figures, they would all hit approx. 90FPS +/- 5 but that figure saw the GPU up at 50% utilisation.

 

I still don't think that's the answer though as when it was running at its strongest the GPU was being taxed as the temps were up to 65°C.... even with up to 50% utilisation the temperature doesn't go over 49°C so I believe that may just be an effect of the buffer itself.


Something else I just remembered. I also started messing around with the Texture_Bandwith_Multi setting. I had defaulted this back to 40 a while back as I wasn't really noticing a difference. Today I decided to start typing in crazy figures. With Texture_Bandwidth_Multi=400 I saw a 10fps increase.

 

Not sure why that's happened.

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Not clear to me why higher GPU usage would be a good thing...

 

For a 1080 GPU, any usage above 50% sounds questionable.

 

I would go back to a clean fsx.cfg file and set fps to 30 in fsx.

 

Then see what improvements you can make from there..

 

Also check if anything is running in the background when starting FSX.

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GPU usage is always higher without addons.

I'm struggling to see the logic in this. How does installing add-ons reduce GPU usage?

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I'm struggling to see the logic in this. How does installing add-ons reduce GPU usage?

 

Easy. Add-ons have FSX issue more draw calls (on the CPU side) than the default setup, and they have more work to do for shaders on the GPU side, because it renders way more stuff. All those custom autogen objects that are in payware that didn't exist in the base setup.

 

Depending on your setup, your GPU may not have enough shaders, so the everything has to essentially sit in queue (PCIe bus) before the GPU can access it. It's like waiting at a red light and when your GPU has some shaders freed up, the content moves from the bus to the GPU.

 

Then again, just because all your available shaders on the card are being used doesn't equal GPU usage being 100%.

 

Other things contribute to lower GPU usage. If your framerate is capped in any way (vsync, internally or externally, etc), your GPU usage will be lower as well. Regardless of whether you have add-ons or not.

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