In my case, with the Ryzen 5600x, disabling SMT (the AMD HT) and reverting to DX11 were the 2 main keys for success regarding smoothness, stability and lower temperatures and power consumption.

In P3D v5 and v6  it's crucial  to disable SMT in order to get acceptable temperatures in the CPU cores. Unfortunately I can't revert to DX11 in P3Dv5 and v6 😕

 

I’m finding it’s smoother more stable with HT off. 

Both CPU (13600 / 13900) where running with HT off .

13900 5-5.7 GHz Boost

13600 5-5.3 GHz Boost 

 

I also have an i9 9900K and HT off provides the smoothest experience both in MSFS as well as P3D.

As far as I can remember (FSx/P3D), with my i7-10700KF, Hyperthreading OFF has always give better result on my setup. I didn't try HT ON for... years 😉

Edited December 8, 20232 yr by vbazillio

11 hours ago, iFlySimX said:

Hello all! 

I decided to do some testing with my i9-9900k as I've been getting some stutters on the ground with the Fenix A320. 

I turned Hyperthreading OFF in the BIOS and it seems a lot smoother and gives me higher FPS. Is that expected, any reason why I SHOULDN'T keep Hyperthreading off?

Thanks for pointing out that.

I was skeptical but I did a similar test in my favorite CPU limited testing environment (A310 @ EDDF25C, real time traffic) and for the first time I found the same results!

Always have hyper threading off for games. Single thread performance is much more important.

Most games do not support multi threading and until they do  there is no benefit in having HT on.

HT has it’s uses if you are running demanding multiple tasks simultaneously but until most games support true multi threading ( that’s still a long way off ) HT when running a game merely increases latency. 

Hence the performance increase seen when it’s off.

I have an Intel 13900k.  I have found the best setting for me is to remove all e-cores (which are useless in normal usage anyway, and in MSFS), reduce p-cores to 6, and turn off all hyperthreading.

I know this sounds counter-intuitive, and probably crazy, but it works for me in MSFS, and gives the smoothest experience, with cores only reaching 85-87C, so no thermal throttling (which may be the key).

Reasons for this I believe are as the following...

MSFS still appears to use only two cores at high utilisation, and my other 4 cores run at below 50%, but this seems to be enough for the sim.

At default (all cores plus HT), I always had the two main cores going to 100C and so thermal throttling was occurring. 

I have read that any CPU cache unused by the cores that are turned off is utilised by the remaining cores.  As we know, extra cache significantly benefits MSFS performance, as proven with the  AMD X3D chips. 

For those that want to say 'I shouldn't  be hitting 100C on the two main cores at default', and "your cooling is out of whack", don't bother.  These chips are known for this. 
I have a Corsair 150i water cooler with the block properly seated, MX-5 thermal paste, and the motherboard mod to ensure proper seating on the CPU.
The fact that I can run MSFS 4K ultra 60 FPS now with the two main cores flat out for hours in the sim (nearly always 100% utilisation) and staying well below 90C proves this.

PS.  I did try to under-volt the 13900k, but even -0.05v gave me blue screens.  But it is completely stable at default voltage. I know every chip is different, and some people can do -0.15v with a bit of tweaking.  
The 13900k is pushed right to the limit by Intel, and overclocking is not worth it either - it just makes things worse in terms of temps and stability.

This is why I am not swapping out to a 14900k, as the increase in performance is negligible, and the temperatures are no better. 
The 14900 is just marketing and making it look like Intel are doing something.  It is a poor release, and AMD will wipe the floor with them if they are not careful.  Intel need to get their act together for the 15000 series.

Unless you are doing video editing, all these cores are useless to the average user.  Cinebench results are just willy-wangling!  
An octa-core at most is all that is required for games and day-to-day windows use.  You still can't beat raw Gigahertz and instructions per second for applications like MSFS. 
To hell with all  those useless extra cores!  And if you want to do video editing, get a Threadripper or something.

Edited December 8, 20232 yr by bobcat999

Interesting- I’m on a relatively ancient 11900K (8 cores) and have always had HT on… perhaps there’s a benefit to turning it off. Will try that soon… thanks!

Edited December 8, 20232 yr by cavaricooper

I've disabled SMT on my 5800X3D and done a little testing.  I believe MSFS feels a little smoother but have noticed no significant difference in FPS or temps so far.  I will leave it like this for a few days and see how it feels in a few different scenarios.

One thing to note is that doing this disables sleep mode so you can't put your PC into sleep. Not an issue if you don't use that feature though.

Update - Flight over London with ORBX Landmarks and FSLTL traffic from EGLC to EGLL - Locked at 40 FPS at 1440 rez.  Hardly aa stutter and FPS did not drop below 37 FPS for the entire flights - That sounds like a good result.  Also flew from Salzburg to Innsbruck in live weather with heaps of addons.  Result was similar except around Salzburg Airport and city where I always get poor performance due to having too many addons.  The updated snow post SU14 was great though.

Edited December 8, 20232 yr by cianpars

2 minutes ago, cavaricooper said:

Interesting- I’m on a relatively ancient 11900K (8 cores) and have always had HT on… perhaps there’s a benefit to turning it off. Will try that soon… thanks!

Nothing to be lost from trying it.  If you don't see any improvement you can just turn it on again.

Started to do some tests with DX12. DX12 with HT ON has always been bad for me but now with HT OFF, it's not bad at all. Still need to do some more testing. 

1 hour ago, bobcat999 said:

I have an Intel 13900k.  I have found the best setting for me is to remove all e-cores (which are useless in normal usage anyway, and in MSFS), reduce p-cores to 6, and turn off all hyperthreading.

I know this sounds counter-intuitive, and probably crazy, but it works for me in MSFS, and gives the smoothest experience, with cores only reaching 85-87C, so no thermal throttling (which may be the key).

Reasons for this I believe are as the following...

MSFS still appears to use only two cores at high utilisation, and my other 4 cores run at below 50%, but this seems to be enough for the sim.

At default (all cores plus HT), I always had the two main cores going to 100C and so thermal throttling was occurring. 

I have read that any CPU cache unused by the cores that are turned off is utilised by the remaining cores.  As we know, extra cache significantly benefits MSFS performance, as proven with the  AMD X3D chips. 

For those that want to say 'I shouldn't  be hitting 100C on the two main cores at default', and "your cooling is out of whack", don't bother.  These chips are known for this. 
I have a Corsair 150i water cooler with the block properly seated, MX-5 thermal paste, and the motherboard mod to ensure proper seating on the CPU.
The fact that I can run MSFS 4K ultra 60 FPS now with the two main cores flat out for hours in the sim (nearly always 100% utilisation) and staying well below 90C proves this.

PS.  I did try to under-volt the 13900k, but even -0.05v gave me blue screens.  But it is completely stable at default voltage. I know every chip is different, and some people can do -0.15v with a bit of tweaking.  
The 13900k is pushed right to the limit by Intel, and overclocking is not worth it either - it just makes things worse in terms of temps and stability.

This is why I am not swapping out to a 14900k, as the increase in performance is negligible, and the temperatures are no better. 
The 14900 is just marketing and making it look like Intel are doing something.  It is a poor release, and AMD will wipe the floor with them if they are not careful.  Intel need to get their act together for the 15000 series.

Unless you are doing video editing, all these cores are useless to the average user.  Cinebench results are just willy-wangling!  
An octa-core at most is all that is required for games and day-to-day windows use.  You still can't beat raw Gigahertz and instructions per second for applications like MSFS. 
To hell with all  those useless extra cores!  And if you want to do video editing, get a Threadripper or something.

You have the exact same system as me.  Are you using the bios to turn off the cores or can you accomplish this via software?

I've turned HT off for the simple fact that my CPU runs cooler (average temps 48c in MSFS) and went from 5gHz to 5.2. on all 8P cores.

Edited December 8, 20232 yr by CarlosF

I compared and contrasted all this stuff years ago and found that I got the best performance with HT turned off on the Core that ran the main thread in MSFS but left HT on, on all the other Cores. So i have 10 physical cores or 19 logical cores. Well, I suppose its time to revisit to see it there is any obvious difference with HT on vs HT off. But remember if you think your not sure if you can see any difference of if you have a feeling it might be slightly better, that is within the margin of error of your prejudice so snap out of it!🤣