Re: 3GB in 2 DIMM slots!

On Tue, 20 Oct 2009 19:10:47 -0700, Brent Nora wrote:

I have only two DIMM slots with a 2GB stick in one on my
desktop running vista 32bit,

You say "only two," but depending on what apps you run, that may be
enough for you, and any more may do next to nothing in your case.

should I install an identical
2GB to activate dual channel, making it 4GB, or should

That may give you some small improvement in performance, but not
necessarily a lot.

I just get another 1GB to stay within the 32bit OS
limitations of 3GB?

There is no 3GB limitation. How much you can access varies, depending
on your hardware (although it's usually *around* 3GB). Here's the
scoop on the subject:

All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB
address space (64-bit versions can use much more). 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

Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.

each slot can operate with a maximum
of 4GB RAM sticks a total of 8GB. And if I do go to 4GB,
can't Vista allocate the video memory from the excess
of the 3GB limitation,


and can't I use the extra as well


Ken Blake, Microsoft MVP (Windows Desktop Experience) since 2003
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