PAE switch in 32bit Vista

  • Thread starter Thread starter Steve
  • Start date Start date
Steve said:
I have 32bit Vista Business and since yesterday there is 4 GB of RAM. Now,
I've checked
http://msdn.microsoft.com/en-us/library/aa906211.aspx and added "BCDEdit
/set PAE forceenable" but Task Manager still can see only 3070 MB Physical
memora.
How to setup Vista to use whole 4 GB RAM?
Click to expand...

This is normal and to be expected. Many 32-bit device drivers would stop
working if PAE adressing was enabled. So the PAE switch does not make any
more memory available, for desktop versions of 32 bit Windows.

If you have 32 bit Windows, then around 3.1GB (plus or minus a bit) is the
maximum RAM you will *ever* be able to use. The total address space is 2^32
== 4GB; and about 0.5 to 1.0 GB of this needs to be put aside for hardware,
such as video memory. That leaves around 3.0 to 3.5 GB RAM useable, on most
machines - 3070MB sounds pretty typical.

See this Microsoft KB article for details :
http://support.microsoft.com/kb/929605

If you really, really want to use all 4GB of RAM, then you'd need to run the
64 bit version of Windows. But whether that's worth it, depends on whether
you're memory-constrained today.

Hope this helps,

Andrew
 
Steve said:
I have 32bit Vista Business and since yesterday there is 4 GB of RAM. Now,
I've checked
http://msdn.microsoft.com/en-us/library/aa906211.aspx and added "BCDEdit
/set PAE forceenable" but Task Manager still can see only 3070 MB Physical
memora.

How to setup Vista to use whole 4 GB RAM?
Click to expand...

You don't. Microsoft's client operating systems (XP and Vista)
implement PAE only to support DEP (Data Execution Prevention), not to
expand the address space. Server OSs do use PAE to access more RAM.

See here for a discussion of why you can't use all 4GB:
http://members.cox.net/slatteryt/RAM.html
 
I have 32bit Vista Business and since yesterday there is 4 GB of RAM. Now,
I've checked
http://msdn.microsoft.com/en-us/library/aa906211.aspx and added "BCDEdit
/set PAE forceenable" but Task Manager still can see only 3070 MB Physical
memora.

How to setup Vista to use whole 4 GB RAM?
Click to expand...


Sorry, but you can't.

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.
 
Hi Steve
(snip) from http://support.microsoft.com/?kbid&ID=929605
Note When the physical RAM that is installed on a computer equals the
address space that is supported by the chipset, the total system memory that
is available to the operating system is always less than the physical RAM
that is installed.

(snip) from http://support.microsoft.com/kb/946003/
After you install Windows Vista Service Pack 1 (SP1), the memory (RAM) value
reported by Windows Vista may increase if the following conditions are true:
a.. The system BIOS has reserved physical memory for graphics or for other
peripherals.
b.. Your computer has more than 3 GB of system memory installed.
c.. ...This change in Windows Vista SP1 is a reporting change only.
If you are running programs that would benifit by having more than 4GB of
RAM you would need the 64 bit version of Vista
There is nothing wrong with your system, you need to learn whats going on
with memory and how it is used/allocated. Below are some links to
information to help you get started.
http://support.microsoft.com/?kbid&ID=929605
http://support.microsoft.com/kb/946003/
http://support.microsoft.com/kb/935268/

H Brown
 
If you have 32 bit Windows, then around 3.1GB (plus or minus a bit) is the
maximum RAM you will *ever* be able to use. The total address space is
2^32 == 4GB; and about 0.5 to 1.0 GB of this needs to be put aside for
hardware, such as video memory. That leaves around 3.0 to 3.5 GB RAM
useable, on most machines - 3070MB sounds pretty typical.

See this Microsoft KB article for details :
http://support.microsoft.com/kb/929605
Click to expand...

I have Intel Crestline i965M chipset, which is not listed on that KB, and
regardless all comments I can't use more than 3070 MB RAM.
Thank you guys.
 
I have Intel Crestline i965M chipset, which is not listed on that KB, and
regardless all comments I can't use more than 3070 MB RAM.
Click to expand...


Regardless of what's listed in that article, almost nobody running any
32-bit client version of Windows can use substantially more than that.
Please read the reply I sent to this thread yesterday. It explains
why, and points out that 3.1GB (almost exactly your amount) is a very
typical maximum amount that you can use.
 
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