I have been using fsx with hyperthreading turned off and and affinity value of 12 (this value seems to offer me the best performance). I then got the idea whether I could turn hyperthreading on, but tell fsx to use only the last two real cores, as an affinity mask of 12 says (12=1100). So, I decided to use an affinty value of 160 (160=10100000) because this value only uses the last two real cores and non of the virtual cores as an affinity value of 12 also does. Unfortunately, although I seem to be getting the same fps, when I pan around, especially in areas with much autogen, my frames seem to drop to the low teens. With hyperthreading off and affinty mask of 12, the frames stay pretty much constant (25-30 at fsdreamteam kjfk trial version on final approach to 31L) while with hyperthreading on and affinity mask of 160 (which should, theoretically offer me the same results) looking forward in the cockpit with the same plane, I get the same 26-30 fps, but panning around, these lower to 13 (they seem to stabilize again after 3-5 seconds). Is there anything I could add to my FSX.cfg to fix this, or is this just a limitation of FSX with hyperthreaded cores. (I would like to leave hyperthreading on all the time as I find it a pain to restart my rig, go into bios, and load my hyperthreading on overclock settings each time I need the extra performance).

Well, with HT on all 8 cores are virtual. You have two virtual cores created for each physical core, so you can't really assign a "real core" to anything

Well, with HT on all 8 cores are virtual. You have two virtual cores created for each physical core, so you can't really assign a "real core" to anything

Okay, so I'm guessing FSX doesn't like virtual cores then, and that is why I'm getting this problem?Do you think my problem would be fixed by adding an affinity value of 240 (which equals 11110000 so that both virtual cores created from each core will be working thereby eliminating the initial texture loading that I am seeing?).

Okay, so I'm guessing FSX doesn't like virtual cores then, and that is why I'm getting this problem?Do you think my problem would be fixed by adding an affinity value of 240 (which equals 11110000 so that both virtual cores created from each core will be working thereby eliminating the initial texture loading that I am seeing?).

Yeah, I would try that. 240 or 252

Yeah, I would try that. 240 or 252

Okay thanks a lot. I will post my observations for anyone else having this problem.

I tried 240 and 252, and have found that 252 gives me the same performance as 12 with hyperthreading off.