Installed Physical Memory & Total Physical Memory

The System Information indicates as follows:

Installed Physical Memory: 4.00GB
Total Physical Memory : 2.00GB
Available Physical Memory: 1.05GB

What do these numbers mean? My PC hardware system has two RAM modules
each having 2GB and they are configured for dual channel operation.

So, I think I understand what Installed Physical Memory means. But what
about the Total Physical Memory? Where has 2GB gone? The Available
Physical Memory of 1.05GB appears to indicate 3GB is allocated to the
system overhead, but is this so?

On an x86 Windows you will see a portion reserved by the BIOS for
memory-mapped IO for your devices. This is commonly around 1GB (entirely
depends on which video card you have, etc). However, if you are seeing
exactly 2GB missing then it is likely due to a memory remapping setting in
the BIOS. On an x64 Windows it would almost certainly be the BIOS setting.

"churin" <churin@new.postalias> wrote in message
news:enCza17zIHA.5108@TK2MSFTNGP05.phx.gbl...
> The System Information indicates as follows:
>
> Installed Physical Memory: 4.00GB
> Total Physical Memory : 2.00GB
> Available Physical Memory: 1.05GB
>
> What do these numbers mean? My PC hardware system has two RAM modules each
> having 2GB and they are configured for dual channel operation.
>
> So, I think I understand what Installed Physical Memory means. But what
> about the Total Physical Memory? Where has 2GB gone? The Available
> Physical Memory of 1.05GB appears to indicate 3GB is allocated to the
> system overhead, but is this so?