Vista - 32-bit and 64-bit Vista RAM limit?

I have this question that what is the RAM limit with vista 32-bit and 64-bit?

I've heard that it is 3,2 GB but I've also heard that it would be 4,0GB (because 2^32 = 4.294.967.296. But then 64-bit systems could use over 18 exabytes of RAM, because 2^64 = 18.446.744.073.709.551.616? Isn't that a little too much o.O).

I've also heard that Vista with SP1 ´recognizes´ 4GB of RAM (earlier windows reputedly recognized only 3GB of RAM so does this mean that from Vista SP1 windowses recognize that 4th GB of RAM but can't use it?).

Basically 4gb for x86 vs 128gb for x64, there's a good article here about it (takes a while to load) 32-bit Windows Vista vs. 64-bit Windows Vista - Vs. system memory - Softpedia.
I have 4gb on my 32-bit systems and all of them use approximately 3.33gb of it with my video card taking up some of that. As you said, Vista does see 4gb but can't use it all. But then the definition of "see" and "use" gets rather complicated.

You'll read in that article that it's the design of the operating systems that effects it.

Karmic Koala wrote:
--
Jane, not plain 64 bit enabled :-)
Batteries not included. Braincell on vacation ;-)
MVP - Windows Desktop Experience 2007-2009

Karmic Koala wrote:http://msdn.microsoft.com/en-us/library/aa366778.aspx

--
Jane, not plain 64 bit enabled :-)
Batteries not included. Braincell on vacation ;-)
MVP - Windows Desktop Experience 2007-2009

"Karmic Koala" <guest@xxxxxx-email.com> wrote in message
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32bit Vista will report 4gb, but still only use 3gb or thereabouts..

64bit Vista can see and use between 8gb and way more depending on Vista
version..

--

Mike Hall - MVP Windows Experience
http://msmvps.com/blogs/mikehall/

Go to the link below to learn the answer to your question.
http://support.microsoft.com/kb/929605

H Brown
"Karmic Koala" <guest@xxxxxx-email.com> wrote in message
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Karmic Koala <guest@xxxxxx-email.com> wrote:
32-bit Vista has an address space of 4,294,967,296 bytes, as you
calculated. Some of that has to be used for BIOS, Video RAM and a few
other things, so you can actually use only 3.2 - 3.5 GB of RAM. See
http://members.cox.net/slatteryt/RAM.html

You also calculated the maximum possible address space for a 64-bit
machine. None of Microsoft's 64-bit operating systems implement a fill
64-bit address space. 64-bit Vista Home Basic will handle 8GB, Home
Premium 16GB, and the other versions will take 128GB.

--
Tim Slattery
MS MVP(Shell/User)
Slattery_T@xxxxxx
http://members.cox.net/slatteryt

Hi, Koala.
Vista x86 can use all the 4 GB of RAM. But some of that use is for video
RAM, drivers and other functions that you have no control over, leaving
less - typically about 3.2 GB but variable depending on YOUR hardware - for
you to decide how to use.

Suppose your local post office has 4,096 mailboxes available, but the PO
reserves 800 of those boxes for its own use. If there are only 1,000 mail
patrons in town, then there is no shortage and everybody gets their own
mailbox. When the town grows to 2,000 or even 3,000, there is still no
problem. But when another thousand patrons arrive, only about 200 will get
mailboxes. The other 800 boxes are there and they are not being wasted.
They are already in use (or reserved for something important).

The full 4 GB is being used, but you don't get to specify how some of it is
being used.

Vista SP1 did change the way the 4 GB is being reported to the user, but did
not change anything behind the curtain.

RC
--
R. C. White, CPA
San Marcos, TX
rc@xxxxxx
Microsoft Windows MVP
Windows Live Mail 2009 (14.0.8064.0206) in Win7 Ultimate x64 RC 7100

"Karmic Koala" <guest@xxxxxx-email.com> wrote in message
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"R. C. White" <rc@xxxxxx> wrote in message
news:eypCuM73JHA.1092@xxxxxxThat's an excellent analogy of 32 bit memory mapping. I've used it
myself, but had the boxes reserved for large volume mail receivers
rather than the PO, itself.

What's often overlooked in 32 bit memory map explanations is that
the 4GB space is divided, with 2GB allotted for applications, and
2GB for the OS. Also, most 32 bit apps can't use more than 2GB
of memory. In order for 32 bit apps to use more than 2GB, (4GB
is the maximum), two conditions must be met. The application
has to be large address aware, and run on 64 bit Vista, or the
"set userva" setting must be applied to the Vista "bootmgr",
(Boot Manager), file. A safe value for userva is 2700, which,
in your example above, would allot 2700MB to applications,
500MB to Vista, and 800 to hardware resources. This can also
be applied to XP by adding "/3GB /userva=2700" to the boot
line in the boot.ini file. If hardware used more than, or less
than, 800MB, the userva value would be modified accordingly.

Even though Vista 64 may be able to handle more than 4 gb, be sure your
computer chipset can handle the ram.

"Karmic Koala" <guest@xxxxxx-email.com> wrote in message
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