How many physical cores is best for P3D?

[Ray Proudfoot]

This is directed to the tech chaps at LM so I hope you can help us. The Affinity Mask settings recommended with v5.3HF2 have made a sizeable improvement to performance even with my i7-8086K with HT enabled. But we now have new CPUs coming out with up to 24 physical cores.

What is the ideal number of cores that P3D (current and maybe v6) can take advantage of? All of them or is there an upper limit?

It would be helpful to know when deciding whether an AMD or Intel CPU is the best way to go.

Thanks!

[Ray Proudfoot]

I’m running v5.3HF2 but will consider v6 should it prove a worthy upgrade.

As I understand it from a reliable source v5.3 cannot use more than 6 cores. So with some CPUs having as many as 24 is that overkill? But if more = better that goes against what my source says.

As for running addons such as ChasePlane and Active Sky I use SimStarterNG which can assign executables to specific cores. I’ve been doing that for a while.

So my original question remains. What is the upper limit beyond which no gain is achieved?

[JorgenSA]

Ray, check out this thread:

https://www.avsim.com/forums/topic/5797 ... servation/

Some of the discussion goes over my head, but I believe the general drift is that you might want to question your "reliable source".

But, as I said, some of this is in the stratosphere, above my service ceiling.

Jorgen

[Ray Proudfoot]

Hi Jorgen. There were a few other topics along the same line and I learned how to set mine up for v5.3HF2 which made a real difference.

SteveW certainly knows his stuff. Anyway, v6 may take that further but until it’s released LM won’t say anything. Perhaps when it is they can educate us as to the ideal number of cores and whether Hyperthreading is advisable or not. I suspect not with so many physical cores.

[JorgenSA]

Regarding HT, I can only say what I have read about the opinions of others: that "generally it is preferred to have HT off".

I have tried with it off and on, both in FSX and P3D, and I have not been able to see any difference with my present CPU, or with my former I7-7700K.

Jorgen

[Ray Proudfoot]

I have it on at present and as I’m selling this pc soon I won’t change anything. But it generates more heat so I’ll leave it off for the new computer. Probably going to AMD and the 7950X3D.

[Sabre57]

I just happened to do a lot of testing with HT on this past weekend, 5.3H2. I'm on an I9-9900 non-K cpu with a 3090. I tested with the default affinity mask as well as limiting P3d to various CPUs, including various combinations of virtual cores on and off. In all cases the sim did not work as well with HT off. Biggest impact was to scenery loading and getting blurries that never went away. Frames were good though. I also fiddled with FFTF and it had no effect. As soon as I turned off HT viola, my blurries went completely away. I have no idea why.

[Ray Proudfoot]

My take on HT is this…

ON Shorter loading times but more heat. Maybe not as good at overclocking.

OFF Longer loading times and runs cooler. Best for overclocking.

FPS maybe the same unless you can clock slightly faster with HT Off. But we’re talking a few % which you may never notice.

What I would like to do is clock core 0 faster than all the other ones since that determines best fps in P3D. Not wise enough to do that without guidance.

[Sabre57]

What I would like to do is clock core 0 faster than all the other ones since that determines best fps in P3D. Not wise enough to do that without guidance.

I would also like to know how to do this. I would also like to know how to determine what the various speeds are for all of the cores.

[Ray Proudfoot]

I would also like to know how to do this. I would also like to know how to determine what the various speeds are for all of the cores.

You can use MSI Afterburner and Riva Tuner SS to see core speeds.