it realy dosent matter to the point that you have not read or taken in any of the comments that have been posted here, i have said that a 32 bit application cannot use more than approx 3 gig of ram, so bf3 cannot have 4gb of ram to itself because it cannot acces 4gb of ram due to it being a 32 bit application,
I think there is a thread about this somewhere. A 32bit application can address 2 GB or 4 GB, if marked LAA-compatible.