Mem Max Limits WTF

Bl8ckr0uter

Ok so I am building a computer and I was looking at the max limits of ram in the 64bit version of XP (128Gb). I was looking on this webpage and I then saw something strange: The 32bit copies of windows server os can support 4-128gb of ram. WTF!?!??! 32 bit oses can only support (address) like 3.2gb of ram so how can this be? Are the 32 bit copies of the Server OS special? Can someone explain this?

Here is the site that I pulled this info from:

Memory Limits for Windows Releases (Windows)

dynamik

Research PAE: Physical Address Extension - Wikipedia, the free encyclopedia

tiersten

The short answer is that to properly support 4GB+ memory with a 32 bit OS you need PAE enabled in the OS but you also need PAE aware drivers as well for your hardware. As there are 64 bit editions of Windows now, hardware vendors generally don't bother creating such drivers. There are various sites out there which show you how to remove the 4GB limitation but you're just asking for trouble by doing that. If you want support for > 4GB then use a 64 bit edition.

Bl8ckr0uter

dynamik wrote: »

Research PAE: Physical Address Extension - Wikipedia, the free encyclopedia

Interesting.

tiersten wrote: »

The short answer is that to properly support 4GB+ memory with a 32 bit OS you need PAE enabled in the OS but you also need PAE aware drivers as well for your hardware. As there are 64 bit editions of Windows now, hardware vendors generally don't bother creating such drivers. There are various sites out there which show you how to remove the 4GB limitation but you're just asking for trouble by doing that. If you want support for > 4GB then use a 64 bit edition.

Ok now since the OS is still using the 32 bit addressing, if I were to go into the bios (or into windows itself) of a machine that was using PAE would it show 4gb (or whatever the limit of the motherboard is) or the actual amount of Ram (lets say 64 gb).

tiersten

knwminus wrote: »

Ok now since the OS is still using the 32 bit addressing, if I were to go into the bios (or into windows itself) of a machine that was using PAE would it show 4gb (or whatever the limit of the motherboard is) or the actual amount of Ram (lets say 64 gb).

It would show whatever it can address.

The actual software running on a 32 bit server edition would still be limited to an address space of 4GB. Of that, around 1-2GB of address space is taken up for system usage. The advantage and reason why they went to this extra hassle with an extra layer of page tables is that you can have multiple applications running each with their own 4GB address space.