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?).


--
Karmic Koala

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'
(http://news.softpedia.com/news/32-bi...ta-64312.shtml).
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.


--
Ex_Brit

::*-Peter-*::
Toronto, Canada
XP Pro SP3, Vista Ultimate SP2, Windows 7 RC
P4 HT @ 3.0ghz, 4gb DDR, 700gb HDD

"R. C. White" <> wrote in message
news:...
> Hi, Koala.
>
>> *recognize* that 4th GB of RAM but can't *use* it?).
>
> 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
>
> Microsoft Windows MVP
> Windows Live Mail 2009 (14.0.8064.0206) in Win7 Ultimate x64 RC 7100
>

That'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" <> wrote in message
news:...
>
> 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?).
>
>
> --
> Karmic Koala

"Ian D" <> wrote:


>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.

No, you're confusing physical and virtual memory. Each process running
in Vista (or XP or ...) is allocated a 4GB virtual memory space
(assuming you're on a 32-bit machine. I'm not sure how big the virtual
space is on a 64-bit machine). 2GB of that virtual space is reserved
for the OS. There will be *many* virtual spaces existing at any one
time. The virtual storage system keeps pieces of all of them in
physical RAM all the time, and other pieces in the swap file. It uses
various techniques to try to make sure that the bit that's needed is
in physical RAM when it's needed. But there's no OS vs application
division in physical RAM.

--
Tim Slattery
MS MVP(Shell/User)

http://members.cox.net/slatteryt

"Tim Slattery" <> wrote in message
news:...
> "Ian D" <> wrote:
>
>
>>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.
>
> No, you're confusing physical and virtual memory. Each process running
> in Vista (or XP or ...) is allocated a 4GB virtual memory space
> (assuming you're on a 32-bit machine. I'm not sure how big the virtual
> space is on a 64-bit machine). 2GB of that virtual space is reserved
> for the OS. There will be *many* virtual spaces existing at any one
> time. The virtual storage system keeps pieces of all of them in
> physical RAM all the time, and other pieces in the swap file. It uses
> various techniques to try to make sure that the bit that's needed is
> in physical RAM when it's needed. But there's no OS vs application
> division in physical RAM.
>
> --
> Tim Slattery
> MS MVP(Shell/User)
>
> http://members.cox.net/slatteryt

I wasn't talking about RAM, but memory space in a simplified
manner. Yes, I know that each application has it's own 4GB of
virtual address space, and that space is mapped to RAM as
required. The point is that, if an application can't use more than
2GB of addressing space, it obviously does not have access
to more than 2GB of physical memory. MS itself says that
increasing application address space via /3GB and userva i
ncreases access to physical memory. This, of course, refers to
systems running 32 bit Windows, with 4GB of RAM.

One application that illustrates this is MS Flight Simulator X.
If the fsx.exe file exceeds about 1800MB when running FSX,
an out of memory error occurs, and FSX terminates. With
FXS SP1, MS made FSX large address aware. Running
FSX SP1 in XP with "/3GB /userva=", or in 32 bit Vista
with "set userva", or in 64 bit Vista, the fsx.exe file can exceed
2GB with no issues. In 64 bit Vista with more than 4GB of
RAM, FSX is able to access a full 4GB. I have found that
Photoshop Elements 6 is also large address aware.