To retrieve accurate information for an application running on WOW64, call the GetNativeSystemInfo function. (see http://msdn.microsoft.com/en-us/library/ms724381%28v=vs.85%29.aspx) On my computer GetSystemInfo on WOW64 returns 32 instead of 48 cores. GetSystemInfo in a 64 bit application returns 48 cores. GetNativeSystemInfo returns 48 cores on WOW64 and in a 64 bit application.
For more complete information about compiler optimizations, see our Optimization Notice.