XP and 4GB RAM

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Osiris

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The problem lies with how Windows XP allocates physical address space for devices. As you all know, XP is a 32-bit Operating System and has a total of 4gb memory space. Hardware devices will take I/O address resources from this 4GB. For Example, the 3.75gb~4.00gb (256mb) memory space is reserved for I/O APIC and BIOS EPROM; 3.50gb~3.75gb is reserved for configuration-space memory-mapping access for PCI Express, 3.25gb~-3.50gb is reserved for PCI Bridge devices such as the IDE Controller, USB Devices, and Onboard audio. When you have a PCI Express graphics card with 256mb of ram, 3gb~3.25gb will be allocated to the first PCI Express graphics card. A second PCI-E card would take another 256mb in the 2.75gb~out of 4gb of memory available for Windows applications. Memory remapping could be a solution, but theres a performance cost and some drivers might fail with the physical address extension enabled. The easy way around this is Windows XP 64-bit OS.
 
ya im getting the 64 bit version for my second comp running an athlon 64 so i wonder. but i only have 1 gig of ram. no need for more right now until vista and then vista will support much more
 
that pretty much explain why my computer got much slower when
I upgraded my ram.

the problem with 64 bit windows is... A lot of stuff don't work with it.

I want to edit video with it, but it won't recognize my hardware encoder card for one
 
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