Phil posted these lines in his blog:--------------------------------------------"FSX SP1:New tweaks In fsx.cfgThere is a tweak to control scheduling of threads on cores. It is not recommended to change these settings unless you have a performance reduction and/or maxed out CPU loads in the PerfMonitor. The tweak isEdit:Fixed a typo here [JOBSCHEDULER]AffinityMask=nwhere n num of cores scheduled1 = 1 core 00013 = 2 cores 00117 = 3 cores 011115= 4 cores 1111"---------------------------------------------What does he mean? There is no such section in my FSX.cfg file. Am I supposed to add those 2 lines or what?Brian

You have to write this section into the Config file. You don't need it for a stock 2 or 4 core installation but if you feel you must,then insert the following lines(for a dual core CPU):[JOBSCHEDULER]AffinityMask=0011and for a quad core it would be:[JOBSCHEDULER]AffinityMask=1111Its pretty self explanatory.John

Should you enter it as 0011 or 2?Manny

As above

I've seen a lot of guys here enter =1, or =2. Seems like its a bit confusing for most. This is the first i have seen where somebody has used 0011, for example.

there are a few differing entries in the "above" ...which?al

It would be nice if Phil Taylor would clarify this for us. Phil?Brian

Guys,I have been playing a bit with AffinityMask over the last few days and it is pretty simple really. The number you enter converts to a binary number which sets what cores will be used by FSX. By default, I have found that FSX uses as many cores as it finds (eg. dual in my case), without having to set AffinityMask.The following values of AffinityMask will use the following cores (assuming you have that many in the first place, otherwise it will just use what you have). The first number is what you set AffinityMask to, the second number is what that number's equivalent is in binary and the comment is what cores are used: 1 = 0001 = use core 1 (default for single core) 2 = 0010 = use core 2 3 = 0011 = use core 2 and 1 (default for dual core) 4 = 0100 = use core 3 5 = 0101 = use core 3 and 1 6 = 0110 = use core 3 and 2 7 = 0111 = use core 3, 2 and 1 8 = 1000 = use core 4 9 = 1001 = use core 4 and 110 = 1010 = use core 4 and 211 = 1011 = use core 4, 2 and 112 = 1100 = use core 4 and 313 = 1101 = use core 4, 3 and 114 = 1110 = use core 4, 3 and 215 = 1111 = use core 4, 3, 2 and 1 (default for quad core)If you want to verify, use windows task manager to see which cores are in use for the various settings.Gary

Hi, Both of my cores were either at 100% or close to it so I tried Phil's tweak setting Affinity to 3. My performance before and after the tweak has been good. But, what benefits should I have seen after setting Affinity? Also, did i have any need for it in the first place? According to Phil you could use it if your performance meter is maxed out. Btw, SP1 has been good for me so far. Thanks Aces and Phil...thanks for any help...