I have an early 2012 Macbook Pro with and Intel I7 processor and 16 gigs RAM running Windows 7 Professional 64bit via Bootcamp. I work in Geographical Information Systems as a programmer so most of the applications I am running are 32bit Applications, but tend to use a lot of resources (i.e. ArcGIS, SQL Server Express, Visual Studio, etc.).

I have been noticing that when I have multiple instances of either the same 32bit application or different 32bit applications and they are all working on hefty processing tasks, I am still only topping out at about 30% memory use.

I understand 32bit applications are limited to less than 4gb RAM, but I assumed that one instance could use its own 4gb while another instance could use another 4gb to take full advantage of all the memory I have installed.

Can anyone explain how this works and how I can get my applications to take advantage of all my memory via running multiple instances?