CPU Bottlenecking?

Hi all,

Well I am not an expert in computing so I seek your help to understand what happens.

I play DCS only in VR with a Pimax 5k with Steam SS 200%, Pitool SS 0.5, Ingame SS 1.2 (that's the best combination I found following many advices of fellow users).

My system is as follows:

Core i7 5960X

32 RAM DDR4

RTX 2080Ti

500GB SSD

Win 10

I attached a screenshot of FPSVR so that you see what happens when some demanding situations occur. FPS drops very low and the experience becomes uncomfortable and even unplayable.

I don't understand why the top-end GPU runs at only around half its capacity (56% here) and the CPU only 16%.

My system doesn't preform at its maximum at all.....

Is this CPU bottlenecking???

Even in free flight I get 50 FPS which i accept but the GPU never exceeds 60% and the CPU 20%.

If yes then i could replace the CPU but with which one? My motherboard is an X99 which I think is not compatible with most of the recent CPUs.

Thanks

At first check NVIDIA CPL settings for max performance (avoid optimal).

My system is as follows:

 

Core i7 5960X

 

I don't understand why the top-end GPU runs at only around half its capacity (56% here) and the CPU only 16%.

That 16% usage is an average of all the cores on your cpu, as dcs runs on only one core mostly (a 2nd is used for audio processing) ... so, most likely you have a single core at 100% with the remaining close to idle.

Unfortunately, your high end cpu derives its power from using 8 cores in parallel, which is wasted on DCS ... the sim prefers a high single core performance, rather than having so many cores.

For your next dcs processor, look for a 4-6 core unit with the highest single core performance possible, the passmark benchmark gives an accurate measure for SC performance .. yours has a SC passmark of 2000, while a modern processor like the intel core i5 9600K, that costs a quarter of yours, has a SC rating of almost 2700.

I had similar performance issues. Couldn’t work out why my cou usage sat at around 30% and gpu at 50%, yet VR performance was terrible.

After a lot of research and testing, I discovered my dcs.exe was only using 1 core. I changed it to use 2, and had sound issues. I changed it to use All, and suddenly VR was fantastic. No more stutters. I have to set it up each time I fly, but it’s worth it. My CPU usage is now around 16%

Check how many cores your DCS is using, and experiment - if it is only using 1, with it running on All, or 2. To do this (from memory - not at PC), start DCS, once at the main opening page, press on CTRL ALT DEL, Task Manager, go to processes. Select DCS, details, then click on DCS.EXE, right click, select Affinity. If only on core is selected, try select all. Once done, DCS will now use all cores. Put on your VR headset and load a mission. See how the performance is. If it isn’t any better, go back and set Affinity to 2 cores only.

Closing DCS andcrestarting DCS will put it back to using it’s default cores.

Yes I would a agree Single core performance is king in DCS. I have a test I do where I fly around downtown Dubi. I see it drop below the acceptable 45fps that motion reprojection forces, It will drop to around 35fps and become studdery most noticable when looking sideways. When this is happening I see about 35% cpu usage and 75% gpu usage.

If i look at individual cores they are all even at 35%... so where's the bottleneck? What's happening with the CPU? Is the CPU just dividing a 2 core load amongst all the cores?

I have a 5.0ghz 8700k with HT OFF

32gigs ram and a 1080ti

Yes I would a agree Single core performance is king in DCS. I have a test I do where I fly around downtown Dubi. I see it drop below the acceptable 45fps that motion reprojection forces, It will drop to around 35fps and become studdery most noticable when looking sideways. When this is happening I see about 35% cpu usage and 75% gpu usage.

If i look at individual cores they are all even at 35%... so where's the bottleneck? What's happening with the CPU? Is the CPU just dividing a 2 core load amongst all the cores?

I have a 5.0ghz 8700k with HT OFF

32gigs ram and a 1080ti

Delta the results you have monitoring cpu are dependant of monitore software resolution.

With msi afterburner you can increase the resolution and see a different result.

while with 1 sec reso I see nice almost stable % usage for each core, if I set reso to 1/10th of second I see all cores spiking to 100% each in turn very quickly, instead of showing lets say 30% usage on each.

Delta the results you have monitoring cpu are dependant of monitore software resolution.

With msi afterburner you can increase the resolution and see a different result.

while with 1 sec reso I see nice almost stable % usage for each core, if I set reso to 1/10th of second I see all cores spiking to 100% each in turn very quickly, instead of showing lets say 30% usage on each.

Interesting, ill check that out. Thx

Thank you all, guys for your remarks.

I now understand better what is going on.

I will give a try to what JimmyWA suggests and come back.

Now I'm wondering if a 2080ti or 2080ti super would be a waist. Maybe i should spring for one of those 5.4ghz cherry picked 8086k's! :)

After a lot of research and testing, I discovered my dcs.exe was only using 1 core. I changed it to use 2, and had sound issues. I changed it to use All, and suddenly VR was fantastic. No more stutters.

Windows will use all cores by default. you shouldn’t have to change this,unless it was previously set to something else and constrained, either manually or using a utility like process laso or something else.

Windows will use all cores by default. you shouldn’t have to change this,unless it was previously set to something else and constrained, either manually or using a utility like process laso or something else.

Yes with most chipset, but not with x99, x299 etc... anything "bigger" than a i7 x700K (ex : 6800K - 7800k or all "x" processors like 5960x).

In these cases you have the bug "1 core affinity" / "turbo boost".

Yes with most chipset, but not with x99, x299 etc... anything "bigger" than a i7 x700K (ex : 6800K - 7800k or all "x" processors like 5960x).

In these cases you have the bug "1 core affinity" / "turbo boost".

Thank you for the clarification! I’ve been trying to nail down why some rigs only use one core and others default to ALL.

For anyone reading this thread wanting an example of the issue and to see the fix, here is a YouTube vid:

So that is my case (X99 and 5960X), thanks toutenglisse.

Can anyone tell me what is going on with my computer.

I have an i5 4670 cpu and 2070 gpu 16gb ram.

I have only just got an odyssey+ and am playing with the settings and using task manager to watch the cores. Always when I have the headset off my head DCS uses all 4 cores evenly at about 90%.

As soon as I put the headset on it drops back to 2 cores at 100% and 2 at about 30%. When this happens the result is very juddery.

Sometimes all 4 cores keep working at about 90% and the result is excellent.

I have tried the setting earlier in the thread but it doesn't seem to help.

I am flying the same plane su33 in the same setting and circuit each time so that should not be an issue.

When it is running on all 4 cores I can run at high settings.

I have tried the reprojection enable setting but that is not helping.

Any ideas how to get it running on all cores all of the time.

Just an addition to my last post.

If it keeps using 4 cores when I first put the headset on it will keep using 4 until I shut down the program.

If it starts using 2 once I put the headset on it will keep using 2 until I take the headset off.

As soon as I take the headset off it will go back to using 4 cores.

Put it back on and back to 2 cores again.

That is mainly 2 @ 90% and the other 2 @ 30% or so.

Just an addition to my last post.

If it keeps using 4 cores when I first put the headset on it will keep using 4 until I shut down the program.

If it starts using 2 once I put the headset on it will keep using 2 until I take the headset off.

As soon as I take the headset off it will go back to using 4 cores.

Put it back on and back to 2 cores again.

That is mainly 2 @ 90% and the other 2 @ 30% or so.

have your name changed. Your email as a nickname is not good at all.

To your problem, I think you should have more cores for what you intend to do, but I might be wrong.

Hi,

Thanks for the reply.

I'm not sure that I can change my nickname without changing my login but it certainly doesn't worry me who knows my email.

Anyway the issue with the number of the cores is the thing.

If I had more money I would have more cores but I don't.

The real issue is that sometimes I definitely get 4 cores working when I have the headset on and the result is excellent .

BUT most of the time as soon as I put the headset on 2 of the core max out and 2 slide down to 20 or 30%.

I want to be able to get it to run on all 4 all of the time.

Owen

you can play around with process lasso and assign cores as desired.

bitsum.com

Yes with most chipset, but not with x99, x299 etc... anything "bigger" than a i7 x700K (ex : 6800K - 7800k or all "x" processors like 5960x).

In these cases you have the bug "1 core affinity" / "turbo boost".

i wasn't aware of that. i searched around but haven't found any more information on this issue.

do you have links?

what about the 9700K? and Z390 board? are they affected?

i'm not seeing that behavior. dcs is using all cores.

i wasn't aware of that. i searched around but haven't found any more information on this issue.

do you have links?

 

what about the 9700K? and Z390 board? are they affected?

i'm not seeing that behavior. dcs is using all cores.

IIRC many of the 2011 socket cpu's have this issue, the 115x seem to be immune.

IIRC many of the 2011 socket cpu's have this issue, the 115x seem to be immune.

This - since a long time (at least DCS 1.5) DCS takes benefit of 4 cores and more (better fps over 2 cores), but "X series" (lga2011/2066) intel cpus seem to have (seemed to have?) a bad strategy with DCS : 1 core in turbo boost mode (DCS is not the kind of software that would benefit of this).

Common with sockets above 1151. (some K's(?) and all X's)

This issue seems to recently being fixed (what JimmyWA said in other thread).

My source is only DCS forum - users reports.

i7 9700K / i9 9900K are on 1151 socket so they don't have the 1 core affinity behavior.

After the latest update ED appear to have fixed the problem and all cores are now being used by default!

CPU Bottlenecking?

After the latest update ED appear to have fixed the problem and all cores are now being used by default!

hmm... not sure i follow what you’re saying

you’re saying that DCS had code to limit the number of cores used, and this has now been adjusted (fixed) to allow additional cores?

on the release branch, it’s been using all the cores ever since i first checked (about a year ago).

I have Z370 chipset with LGA 1151 socket and I5 8600 CPU; however, Task Manager shows I am using only 1 core when in game 3D. How can I make DCS use all cores? DCSW OB 2.5.5.3 something (latest) and Win 10 1903.