If you have a 4 core processors, they are actually numbered 0-1-2-3 on the computer side, if you bind it to 4 on the SoD patched it will say 3 in your task manager.
If thats not what your referencing, then I don't know what to tell you.
Aside from that, there are known performance issues with using any processor over the second one, probably because its an archaic client we use and its from a time when 2 processors was essentially a brand spankin new idea