The number question in each sim ! 🙂 

Do affinity masks still work?  Or you talking about just rebooting into BIOS and physically shutting it off?  I think I'm perfectly happy to let it use as much power as it wants.  It's not FSX, so it actually understands modern hyperthreaded CPU's.  During my test flights it was using anywhere from 55-65% of my CPU, more during loading, and using anywhere from 10-16GB+ of my 32GB of RAM.  (more while loading)  It seemed to be properly using threads as well.  It looked like it was mostly sticking to non HT cores with sometimes 2-5 of them in use during peak processing like loading the flight.

I just posted a topic on this before i saw your post roi.

With HT disabled- my I7-6700k Skylake CPU will run at 90-100% maxed out usage most of the time.

With HT enabled- it runs 40-60% usage.
MSFS responds very well to Hyper Threading.

With 10 cores, I rather not activate HT and have an overall cooler system. 

Edited August 18, 20205 yr by GCBraun

You don't have to GC. Not all systems will experience high cpu usage.

This is for those that are experiencing high cpu usage.

Hello All,

My experience with 4770K@4,5Ghz with 1080Ti and 32GB Ram was heavy pauses and stutters, GPU never runs higher than 80%. I'm using highend graphics mode without VS (using Nvidia CP Fast Sync and FPS limit 30 in CP). After reducing CPU to 4,1GHZ and enabling HT I'm very happy with great results even over NYC area. So in my case turning HT on (after 7 years of my PC life :-D) helped a lot,

 

Rado

Hyperthreading works by pipelining 2 32bit operations per 64bit execution pipeline. Even though MSFS is a 64bit program, the majority of the operations are probably 32bit floating point and integer operations still, so I would expect a decent amount of extra pipelining with hyperthreading turned on.

Sometimes turning HT off does help things by reducing thread context switching, but only under unusual or extremely 64bit operation heavy workloads. My cursory analysis suggests that MSFS uses a reasonable number of background threads to load scenery, keeping the loads off of the main threads. The more cores you have, the better.

Matt is da Man!

bs

Is that "turn off HT for cooler system" ever going to stop? Work done equals heat and turning off HT doesn't mean that your system does less work. It still does same amount of work with just a bit different pipeline scheduling and all you are doing is handicapping potential maximum performance. If you can't handle that performance then you should consider better cooling or better decisions during planning phase like going with non hyperthreaded processor.

34 minutes ago, radorabatin said:

Hello All,

My experience with 4770K@4,5Ghz with 1080Ti and 32GB Ram was heavy pauses and stutters, GPU never runs higher than 80%. I'm using highend graphics mode without VS (using Nvidia CP Fast Sync and FPS limit 30 in CP). After reducing CPU to 4,1GHZ and enabling HT I'm very happy with great results even over NYC area. So in my case turning HT on (after 7 years of my PC life :-D) helped a lot,

 

Rado

Same situation as you, same PC specs (signature). HT off. If i turn it on my PC crashes after a few minutes into a flight, if i leave it off, it does not. I might lower the overclock to see the difference. Did you lowered the OC voltage also when you went down to 4,1 or did you just leave that for now?

10 hours ago, Lange_666 said:

Same situation as you, same PC specs (signature). HT off. If i turn it on my PC crashes after a few minutes into a flight, if i leave it off, it does not. I might lower the overclock to see the difference. Did you lowered the OC voltage also when you went down to 4,1 or did you just leave that for now?

Hello,

I’m using Asus Maximus Gene VI, and after lowering frequency from 4,5 to 4,1GHz I didn’t modify voltage,I left it on 1,25V and System agent on 1,2V

 

Rado

With my i7 6700K I went from awful/unflyable stutters with HT off (at 4.7 GHZ) to totally smooth with HT on (at 4.4 GHz).

If you're having stutters, one of the first things I'd try is putting HT on.

James

We will need a benchmark to decide this question.

I can tell you this:

Initially I ran the sim on my setup with no HT, CPU at 4.8Ghz. To my surprise, the FPS were extremely low, something like around 20-25fps, sitting solo in Innsbruck in a Pitts, simple daylight, no weather.

I though, nah that can't be... rebooted, enabled HT, lowered speed to 4.6Ghz, and now I am looking at 50fps in the same situation. I can't really explain it.

Specs: 6700k, 1080TI, 32GB RAM, SSD/NVME combo, 2560x1440

Also do not forget to check your memory settings when turning off or on SMT (Ryzen HT).

My Mainboard tends to change memory/fan settings when I change the hyperthreading settings. You will experience the difference between DDR 2000 and DDR 3200. It will be much greater than any hyperthreading influence 😉