I have an HP Proliant DL580 G2 server (4 3ghz xeon mp processors). I understand this to be a 32bit system. Why am I allowed to upgrade to 32 gb of ram if only 4gb are accessible on 32bit systems? I don't necessarily have a need for a 64bit system but I'd definitely take advantage of the additional memory if I could.
The 32 bit Server O/S support more that 4GB of memory using a technology called PAE or Physical Address Extension.
This allowed the 32 bit version of Server 2003 to support 32GB in the Enterprise version and 64GB in the Data Centre version.
Even with this the apps could only use 2GB of ram per instance unless they were written with the ability to use more (up to 3GB) with extra switches in the Boot.ini.