Server has 4GB RAM, Windows displays only 3.25GB??

[adamf]

We've got a new server which has 4GB of RAM. I noticed today that within Windows it only displays the machine as having 3.25GB of RAM (both in the System Properties and System Information). The BIOS on the other hand displays 4GB.

 

My question: Is Windows just reporting it wrong or is it only recognising 3.25GB of RAM?

 

Has anyone else experienced this?

 

Adam.

[Ric_]

What's 750MB of RAM between friends

 

It's most likely just Windows being odd but you could run some memory checks using UBCD.

[john]

Take its win 2003 32bit? If so, and it may be the same in 64bit, you have to modify the boot.ini file to say /3gb if i remember correctly from doing it to my servers. You can also add in another line of code to help it use that bit more ram whcih is "/userva=3030"

 

Found this - http://support.microsoft.com/kb/823440 fine its going on about Exchange on your box, but it also says on the web that its advisable for any server.

[john]

Except ones that are DC's, Global Catalogues or running Sharepoint Server 2 SP2 upwards, so I semi-retract my last statment

[craiglay]

Is this not some weird bios problem from the days of when 4Gb was insane?

 

http://support.microsoft.com/kb/929605/en-us

 

This suggests chipset limitations will cause this

 

Craig

[john]

No not really, if its a new server, most servers out there will take up to 8gb ram now if not more, its a 32bit windows limitation

[mac_shinobi]

Found this ms kb which may be of use and has some good info :

 

http://support.microsoft.com/kb/283037

[mac_shinobi]

If you add more memory to the system, it is possible that the BIOS will recognize the full amount of physical RAM that is installed in the server but that Windows will recognize only a part of the RAM. If the server has a redundant memory feature or a memory mirroring feature that is enabled, the full complement of memory may not be visible to Windows. Redundant memory provides the system with a failover memory bank when a memory bank fails. Memory mirroring splits the memory banks into a mirrored set. Both features are enabled or disabled in the BIOS and cannot be accessed through Windows. To modify the settings for these features, you may have to refer to the system user manual or the OEM Web site. Alternatively, you may have to contact the hardware vendor.

 

For example, if you are running a system that has 4 GB of RAM installed and you then add 4 GB of additional RAM, Windows may recognize only 4 GB of physical memory or possibly 6 GB instead of the full 8 GB. The redundant memory feature or the memory mirroring feature may be enabled on the new memory banks without your knowledge. These symptoms are similar to the symptoms that occur when you do not add the /PAE switch to the Boot.ini file.

[craiglay]

Sorry, should have read the site I posted. It was regarding Vista.

 

However, I did read somewhere (I'll try to dig out that somewhere) that the system cannot allocate more that 4Gb (32 bit addressing) and that the reserved systems devices have to reside in this limit. Therefore that memory is unaccessable to Windows normally. I'm not sure how this looses ~700Mb but i'll try look it out.

 

Craig

[john]

I belive its 4gb less the page file and the usual system over-head, so if you add your page file on and do the usual 1000mb / 1024mb Gigabyte thing rule you should total 4gb.

[Geoff]

A 32bit system can only ever address 4gb of ram. Run the machine with a 1mb page file and see what happens.

[kingswood]

I believe it is the page file. As Geoff said run it with less and see what happens.

 

[wil0]

Sorry, should have read the site I posted. It was regarding Vista.

 

However, I did read somewhere (I'll try to dig out that somewhere) that the system cannot allocate more that 4Gb (32 bit addressing) and that the reserved systems devices have to reside in this limit. Therefore that memory is unaccessable to Windows normally. I'm not sure how this looses ~700Mb but i'll try look it out.

 

Craig

 

This is correct. Windows can only use 3-GB flat virtual address space, about 700mbs for the kernel and executive components.

 

check this out for the reason why...

http://www.codinghorror.com/blog/archives/000811.html