RAM and 32-bit vs 64-bit?

[bdr122]

As widely discussed elsewhere, Vista 32-bit will not recognize more than
approximately 3 MB of installed RAM (caveat #1 - I am aware that there are
some work-arounds for this; caveat #2 - after installing Vista SP-1, windows
will correctly report the amount of RAM you have installed, but will still
not be able to use more than about 3 MB). I have also read that although you
can install much more RAM if you are running Vista 64-bit, the OS itself (or
at least applications run on it) take more RAM to run.

In light of this, here's my question: all other things being equal, is it
better (in terms of performance) to run Vista 32-bit with 4 MB of RAM (where
only about 3 MB will actually be used) or to run Vista 64-bit with 4 MB of
RAM (where all 4 MB will be recognized, but where more RAM is required to run
applications)?

 

[Rick Rogers]

Hi,

Running a 32-bit application in a 64-bit installation of Vista will not
require any more ram allocation than running the same application in a
32-bit installation. You would need to have 64-bit applications to take
advantage of the extra ram available in the 64-bit versions of Vista. And,
if you're running 32-bit applications in a 64-bit installation, the programs
can still only run from the lower 4GB (not MB) of ram addresses, rendering
the extra ram available useless as far as running applications goes (though
it can still be used for the OS).

Right now, there aren't many consumer-level 64-bit applications, but
eventually that will change. For the vast majority of available software,
you will see no performance benefit whether you use a 32-bit or a 64-bit
installation.

--
Best of Luck,

Rick Rogers, aka "Nutcase" - Microsoft MVP

Windows help - www.rickrogers.org
My thoughts http://rick-mvp.blogspot.com

 

[Mark H]

No matter how much memory you install, _most_ applications can only be
assigned 2GB to function, including the OS. Each will typically use less
than this and give away what is not being used, but when needed, the
pagefile kicks in to make room. So, unless you are running a special
application capable of using more than this 2GB limit (very few), or run
multiple applications simultaneously. It's about even.

Going x64 may allow you to use the entire 4GB of memory for applications by
releasing those addresses shared with your video card, but it is unlikely
you'll find any application that can use it.

Additionally, while Vista may support up to 128GB (certain versions) the
motherboard will typically be limited to 8GB. (A few support more.)

The "biggest" advantage with more memory is the reduction in pagefile use by
giving the OS and applications the memory to work with (up to their
limitation.) In the event you use some special application, such as
video/photo editing, then 64-bit can process more information in the same
amount of time making it more efficient. A few games have used this to
produce more detailed graphics rendering. Running x86 programs on x64
platform suffers a tiny loss in performance that most would never notice.
(If you are simply writing papers, you won't see any difference.)

The more people move to x64 creates the push to get software written for
x64. Then, it will improve.

 

[Steve Thackery]

Going x64 may allow you to use the entire 4GB of memory for applications

by releasing those addresses shared with your video card, but it is
unlikely you'll find any application that can use it.

In fact, even that doesn't always work. You need a co-operative BIOS, which
will move the video memory out of the range 3.xG to 4.0G.

In other words, even if you've got Vista 64 with (say) 6G of RAM, there may
still be a bloody great hole in it just below between 3.x and 4.0G.

To let Vista 64 make full use of your RAM, you need to make sure that your
BIOS will shift the video RAM well away from the range covered by your
physical RAM.

SteveT

 

[Victek]

In light of this, here's my question: all other things being equal, is it

better (in terms of performance) to run Vista 32-bit with 4 GB of RAM
(where
only about 3 GB will actually be used) or to run Vista 64-bit with 4 GB of
RAM (where all 4 GB will be recognized, but where more RAM is required to
run
applications)?

3 GB is approximate. My Vista 32 bit system has 4 GB installed and the OS
is able to use 3.45 GB. One of the big factors is how much ram you have on
the video card. My card only has 128 megs, but it's not uncommon for new
cards to have up to 1 GB. The more ram on the video card the more benefit
there is to using Vista 64 bit on a 4 GB system (assuming that video ram can
be mapped above the 4 GB address space as someone else mentioned). You
don't say though what you will use the computer for. Having additional ram
available is only going to improve performance if you sufficiently load the
system.