Memory question

[Swift]

Does Windows Xp support more then 3GB of Memory ( DDR2 ) ?

[IdolEyes787]

x32 XP will only recognize 3 and a bit(it varies) of RAM
x64 up to 128 GB

[Detale]

Does it vary? I thought it was a standard 3.something?

[IdolEyes787]

As I understand it the amount is dependent on the motherboard architecture and the chip set being used.
Anywhere from 2.75 to 3.5GB might show up.Of course that's just what I've read but there definitely is variance.

[Detale]

Ahh. i didn't know that. maybe because I have used all Gigabyte boards with ICH9/10 I get the same reading? Then again my memory couold be failing me and I just assume its the same number.

[Swift]

i only have 2 Gb now but i'll buy tomorow 2 more

[clocker]

I thought the hard limit was @ 3.25GB, then you subtract any that's shared with the video.

[IdolEyes787]

Only relating what I've read.I've seen people claim even 3.7 but you would know better than I.

[clocker]

Not necessarily.
I get all my information from Popular Mechanics.

[MadIrish]

As I understand it....

2 to the power of 32 = 4,294,967,296 bytes
4,294,967,296 / (1,024 x 1,024) = 4,096 MB = 4GB

That's total addressable memory space, which has to include system and graphics ram, PCI memory range, ACPI, and some other minor stuff. In practice therefore, anyone with a 512mb gpu for example has to subtract that from 4gb, but also subtract some other stuff, most likely leaving them with around 3gb.

On computers that have a 32-bit operating system, more than 3 GB of system memory, and with a version of Windows that is earlier than Windows Vista SP1, users will see a larger difference in how much memory is reported as available to the operating system compared to how much physical memory is installed. This is because some physical address space must be reserved as I/O regions for memory mapped peripherals. These I/O regions are allocated between the 3 GB physical address and the 4 GB upper physical address limit.

Physical memory addresses that are mapped to these I/O regions cannot be used to address physical system memory. These addresses also cannot be used to prevent the operating system from using some physical memory that would ordinarily be accessed between the 3GB physical address and the 4GB upper physical address limit. The size of these I/O regions varies from system to system because they determine the type and configuration of the system’s peripherals.

"Due to an architectural decision made long ago, if you have 4GB of physical RAM installed, Windows is only able to report a portion of the physical 4GB of RAM (ranges from ~2.75GB to 3.5GB depending on the devices installed, motherboard's chipset & BIOS). This behavior is due to 'memory mapped IO reservations'. Those reservations overlay the physical address space and mask out those physical addresses so that they cannot be used for working memory. Significant chunks of address space below 4GB (the highest address accessible via 32-bit) get reserved for use by system hardware: BIOS – including ACPI and legacy video support; PCI bus including bridges etc. PCI Express support will reserve at least 256MB, up to 768MB depending on graphics card installed memory", explained Hilton Locke, Microsoft Test Engineer