how to use 16 GB of memory

Is this for 2008 R2 x32 or x64?

If its the 32bit edition move to the 64bit edition.

32bit can address 4GB of memory
64bit can do much much more.

Hi, you must use /PAE switch instead /3GB
Take a look here http://support.microsoft.com/kb/283037

Windows 2008 R2 x64 can address over 16GB of memory (up to 24GB I think) without paying for the Enterprise version.

Physical Address Extension or PAE switch that is used on x86 Operating Systems cannot allocate more than 3GB of memory although once used OS can actually see all of the available memory.
The only thing you can do is to move to 64-bit OS as already suggested.

The limit of Windows 2003 R2 enterprise is 64GB Standard is 4GB

http://msdn.microsoft.com/en-us/library/aa366778(v=vs.85).aspx#physical_memory_limits_windows_server_2003_r2

Please check that PAE is enabled

http://msdn.microsoft.com/en-us/library/aa366796(v=vs.85).aspx 

More info on this. OS Limit is 3GB as I'm aware, but the System limit is 4GB.

The 32-bit limitation is how the system is limited by the addressing space, NOT the vendor. Any more than 4 GB RAM on a 32-bit system is just not seen by the OS, but a portion CAN be used by the BIOS.
Here's the math:
2^32=4294967296 (4.29 GB)
So a 32-bit system can only address roughly 4.29 GB of RAM AT THE MAXIMUM. This is a system limit, not an OS limit.
The PAE extension is built into all modern 32-bit OS (not needed on 64-bit for obvious reasons) and basically allows a second kernel to address the remaining RAM.

http://www.microsoft.com/whdc/system/platform/server/pae/paedrv.mspx

Sorry. i am bit confused. We are using 32 bit R2 Enterprise. Whether i need to use /3gb
 (what is the syntax). or PAE to use. Pl help

Hi, here is example:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Windows Server 2003, Enterprise" /fastdetect /PAE

Hi namanov

    Will it use 16 Gb fully? What we haveused ( /3Gb is wrong? will not use 16GB?)

Pl

Hi dinagaran,
Yes, with PAE switch you will use 16Gb, actually you can use up to 64Gb memory,
Just enter switch in boot.ini file like described in previous post.

Thanks. i wll implement and get back to you shortly

The /PAE switch is necessary to use more than 4GB RAM with a 32 bit OS. The /3GB switch isn't really about RAM usage at all but the virtual address space available to applications. By default the 4 GB virtual address space is divided 2 GB system and 2 GB private per process. The /3GB switch changes this to 1 GB system and 3 GB per process. But only applications that explicitly indicate they are compatible will benefit and most are not.

With the /3GB switch set the maximum RAM that can be used is 16 GB, and in practice it may be less. This switch limits the system virtual address space to 1 GB and that can cause problems, possibly those you are having, particularly with large amounts of RAM.

You should NOT be using the /3GB switch unless it is recommended for applications you are running.

Hi LMiller7,

     I went to the site just now and it is R2 32bit Ent. with 8GB memory. Ruuning Web server in IIS
and in the boot.ini it is like below

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise"
 /noexecute=optout /fastdetect /3GB /USERVA=2900.

As per my understanding out of 3GB (since /3GB) 2900MB has been allotted to process. Correct?

Previously it was  /noexecute=optout /fastdetect /3GB /USERVA=3030. We faced problem. So we changed to 2900.

Since it is 8 GB memory  can we give  /noexecute=optout /fastdetect /7GB /USERVA=6900.

OR
 /noexecute=optout /fastdetect /PAE

i am bit confued

Thanks Namanov and LMiller7. i Will do the same and get back to you shortly.

Great