On Thu, 8 Jan 2009 23:35:58 +0000, amboyangler
<> wrote:
>
> I previously had Windows XP professional on my PC and everything was
> running very smoothly. It also detected that I had 2 different dual core
> CPUS (2 Dual Core Xeons).... However it only detected 3.25 GB out of my
> 4 GB of RAM. I recently installed Vista Home Premium 64 Bit to take
> advantage of the whole 4 GB of RAM but later learned that it only
> supports a single CPU. Here is my question, do you suggest I go back to
> XP and have use of both processors but only have access to 3.25 GB of
> RAM, or stay with Vista Premium using 4 GB of RAM but only using 1 dual
> core CPU? I'm stumped.... 2 other options would be to get Windows XP
> Professonial X64 or Vista Ultimate 64 Bit (which supports multiple
> CPU's)... please help
Two points:
1. All 32-bit client versions of Windows (not just Vista/XP) have a
4GB address space. That's the theoretical upper limit beyond which you
can not go.
But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.
Note that the hardware is using the address *space*, not the actual
RAM itself. The rest of the RAM goes unused because there is no
address space to map it too.
2. Why do you want more than 3.25GB of RAM? The thought that more RAM
always means better performance is wrong. Having more RAM means better
performance only if you had substantial swap file usage with the lower
RAM quantity and adding more eliminates or reduces that swap file
usage.
How much RAM you need to eliminate or reduce swap file usage depends
very greatly on what apps you run, but for the great majority of users
and what they do, 3.25GB is more than enough, and more than that
doesn't improve performance.
--
Ken Blake, Microsoft MVP - Windows Desktop Experience
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