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2 Posts

11404

April 6th, 2005 18:00

4GB RAM on Windows Server 2003 with Perc RAID -- missing memory?

Hello, I have a PE2550 with a PERC 3/DC RAID controller. Windows Server 2003 Standard Edition has been up and running on this box for several weeks. Yesterday I replaced the 4x512MB RAM with 4x1GB RAM, and I am having trouble getting Windows to see all 4GB of the newly installed memory. In the BIOS, I see 4096MB installed, in MSINFO32 I see 4096MB Total Physical Memory, but in System Properties I only see 3.62GB installed! I have tried enabling all combinations of the /3GB and /PAE switches in BOOT.INI, with varying results, none of which got the full 4GB to show in System Properties.

I have begun to suspect that the PERC controller is reserving some of the memory for its own use, as indicated in this thread: http://groups-beta.google.com/group/microsoft.public.windows.server.setup/browse_thread/thread/5f5f6207ecb16a68/e429e7b3ce7d14f6?q=%22windows+server+2003%22+memory+%22system+properties%22&rnum=3#e429e7b3ce7d14f6
>Hello,
>
>Sorry for the late postback. DELL cofirmed that the Perc4 raid controller
>on the PE 2850 Will take 750 MB of the systems RAM for it's use when you
>have 4GB or more of RAM in the machine. This can not be disabled.
>

Can anyone (a Dell employee maybe?) confirm this behavior and point me to any documentation indicating that this is by design? If not, I'd *really* like to know where that 0.38GB is hiding!

Thanks!

Eli Solow

2 Posts

April 6th, 2005 18:00

REPOST for formatting:

Hello, I have a PE2550 with a PERC 3/DC RAID controller. Windows Server 2003 Standard Edition has been up and running on this box for several weeks. Yesterday I replaced the 4x512MB RAM with 4x1GB RAM, and I am having trouble getting Windows to see all 4GB of the newly installed memory. In the BIOS, I see 4096MB installed, in MSINFO32 I see 4096MB Total Physical Memory, but in System Properties I only see 3.62GB installed! I have tried enabling all combinations of the /3GB and /PAE switches in BOOT.INI, with varying results, none of which got the full 4GB to show in System Properties.

I have begun to suspect that the PERC controller is reserving some of the memory for its own use, as indicated in this thread:
http://groups-beta.google.com/group/microsoft.public.windows.server.setup/browse_thread/thread/5f5f6207ecb16a68/e429e7b3ce7d14f6?q=%22windows+server+2003%22+memory+%22system+properties%22&rnum=3#e429e7b3ce7d14f6
>Hello,
>
>Sorry for the late postback. DELL cofirmed that the Perc4 raid controller
>on the PE 2850 Will take 750 MB of the systems RAM for it's use when you
>have 4GB or more of RAM in the machine. This can not be disabled.
>

Can anyone (a Dell employee maybe?) confirm this behavior and point me to any documentation indicating that this is by design? If not, I'd *really* like to know where that 0.38GB is hiding!

Thanks!

Eli Solow

3 Posts

April 7th, 2005 18:00

this is from an asus pc-dl deluxe mainboard manual:
 
when all four sockets are populated with 1Gb DIMMs (total 4GB).
the system may detect only 3,8 gb due to ICH5R resource allocation.
 
perhaps it is the same situiation

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