Windows Server 2008 64-bit Only 3.75Gb RAM Usable

[Charles]

Hopefully a quick question: I am running Windows Server 2008 R2 Enterprise
64-bit on a Dell PowerEdge server. I have 4Gb RAM installed in matched pairs
(2 x 2 x 1Gb). The BIOS is happy that I have 4Gb RAM installed, and the
Windows Memory Diagnostic tool is happy too.

The problem is that Windows reports 4.00 Gb (3.75 Gb usable). So my question
is: where has the rest gone? Why isn't all 4 Gb usable?

TIA

Charles

[Carsten Krueger]

Post by Charles
The problem is that Windows reports 4.00 Gb (3.75 Gb usable). So my question
is: where has the rest gone? Why isn't all 4 Gb usable?

Your bios must support memory remapping.
PCI extensions use the adresse from 3.75 GB to 4.00 GB and you can only use
the RAM in the space if it's mapped beyond 4.00 GB.

greetings
Carsten

[Charles]

Hi Carsten

Thanks for the reply. I don't recall seeing anything about remapping on the
BIOS setup page but I'll double-check. I know that the server can only take
up to 4Gb RAM, so perhaps that means I won't be able to remap above that
anyway.

Charles

Post by Carsten Krueger

Post by Charles
The problem is that Windows reports 4.00 Gb (3.75 Gb usable). So my question
is: where has the rest gone? Why isn't all 4 Gb usable?

Your bios must support memory remapping.
PCI extensions use the adresse from 3.75 GB to 4.00 GB and you can only use
the RAM in the space if it's mapped beyond 4.00 GB.
greetings
Carsten
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[Brian Cryer]

Post by Charles
Hopefully a quick question: I am running Windows Server 2008 R2 Enterprise
64-bit on a Dell PowerEdge server. I have 4Gb RAM installed in matched
pairs (2 x 2 x 1Gb). The BIOS is happy that I have 4Gb RAM installed, and
the Windows Memory Diagnostic tool is happy too.
The problem is that Windows reports 4.00 Gb (3.75 Gb usable). So my
question is: where has the rest gone? Why isn't all 4 Gb usable?

Some graphics cards use system RAM, so is it possible your graphics card has
grabbed the missing memory?