WinXP report 3.25GB memory with 4GB installed

[addyngan]

Hi!

I have a Dell Precision Workstation, running 875P chipset and a P4 3.0C . I have 4 modules of Samsung 1GB ECC memory installed, however, in windows, (task manager, system properties), it only shows up as 3.25G, or 3406844KB. Does anybody has similar experience? Any way i can fix it?

Thanks.

Addy

 

[mechBgon]

From reading zillions of motherboard owners' manuals, that seems to be normal with >3GB of RAM installed. Don't let it bother you, is my advice

 

[Pixle]

Just wondering ....why do you need 4 gigs of ram?

 

[BespinReactorShaft]

Perhaps use some 3rd party memory test program to give yourself a 2nd opinion?

 

[Lonyo]

The limit shown on my old Abit KR7A in the manual was 3.5GB even thought it had 4 RAM slots and could take 4x1GB RAM sticks.
It is probably a motherboard issue.

 

[CraigRT]

Originally posted by: Pixle
Just wondering ....why do you need 4 gigs of ram?

I am curious too. cause that much RAM cannot be cheap

 

[sharkeeper]

First of all, does the system BIOS report all 4096MB? Chances are this is a system limitation. HOWEVER, unless you enable Physical Address Extensions you will not see all 4GB in XP!

If you really need 4GB of RAM, you should be using a workstation mainboard IMO.

Plenty of users *need* 4GB (and more). I've been using 4GB since 2001 and craving for more.

Cheers!

 

[shadow369]

The reason is because systems (32Bit addressing CPU and platforms) have always been able to address up to 4GB of memory. If a system has 256MB to 3GB of physical memory then all the Memory mapped I\O space for the system devices, PCI and or PCI-E config space, ACPI tables, IGD RAM, etc.. are virtually mapped to anything higher than what the physical Top-Of-Memory is in the system. And the OS will report the total amount of physical memory available to it.

However, if a system has 4GB of physical memory and it is only capable of addressing 4GB then there is no place to put the mapped memory as stated above. So the BIOS will limit the Top-Of-Memory to usually around 2.75GB to 3.25GB and use the rest for mapped memory. This BIOS limitation is what will be reported by the OS and will vary from system to system and manufacturer to manufacturer. So basically you don't gain anything by physically using 4GB of physical memory as compared to 3GB as far as what's available to the OS. Although, you will gain the added performance benefit of being able to address the memory in Dual-Channel mode (having 4 1GB DIMM's) compared to Single-Channel mode (3 1GB DIMM's).

There are exceptions to this when you get into a 36-Bit CPU and system that are capable of addressing up to 64GB of physical memory and of course have an OS capable of Physical Address Extensions (PAE Mode). But thats another discussion and I kept this reply geared to the submitters system.