I've long heard that a 32-bit OS can use only up to 3.25 GB
system memory. This is the case with my own computer which has 4
GB installed and TaskManager shows 3.25GB usable memory. However,
while checking around for a new system, I read in some Asus
motherboard manuals that if 4GB or more is installed, a 32-bit
Windows OS may recognize less than 3 GB and they recommend
installing a maximum of 3 GB.
The usable memory size obviously does not drop below 3GB in all
installations of 4GB and 32-bit Windows. So why the heads up from
Asus? Can it happen under certain combinations of hardware and/or
software?
On 8/10/2011 7:04 AM, Pimpom wrote:
> I've long heard that a 32-bit OS can use only up to 3.25 GB
> system memory. This is the case with my own computer which has 4
> GB installed and TaskManager shows 3.25GB usable memory. However,
> while checking around for a new system, I read in some Asus
> motherboard manuals that if 4GB or more is installed, a 32-bit
> Windows OS may recognize less than 3 GB and they recommend
> installing a maximum of 3 GB.
>
> The usable memory size obviously does not drop below 3GB in all
> installations of 4GB and 32-bit Windows. So why the heads up from
> Asus? Can it happen under certain combinations of hardware and/or
> software?
32-bit operating systems, with some sort of Physical Address Extension
(PAE), will never be able to fully utilize 4GB. Windows XP, by default
does not use PAE. It does look like you can enable it:
Grinder wrote:
> On 8/10/2011 7:04 AM, Pimpom wrote:
>> I've long heard that a 32-bit OS can use only up to 3.25 GB
>> system memory. This is the case with my own computer which has
>> 4
>> GB installed and TaskManager shows 3.25GB usable memory.
>> However,
>> while checking around for a new system, I read in some Asus
>> motherboard manuals that if 4GB or more is installed, a 32-bit
>> Windows OS may recognize less than 3 GB and they recommend
>> installing a maximum of 3 GB.
>>
>> The usable memory size obviously does not drop below 3GB in
>> all
>> installations of 4GB and 32-bit Windows. So why the heads up
>> from
>> Asus? Can it happen under certain combinations of hardware
>> and/or
>> software?
>
> 32-bit operating systems, with some sort of Physical Address
> Extension
> (PAE), will never be able to fully utilize 4GB. Windows XP, by
> default does not use PAE. It does look like you can enable it:
>
> http://msdn.microsoft.com/en-us/wind...dware/gg487503
>
> ...but my understanding it is not supported nor recommended by
> Microsoft.
Actually my question was not about being able to use 4GB, but
about the possibility of being reduced to less than 3 (three) GB
if 4GB or more is installed. That possibility is clearly stated
by Asus in their manuals. I've just found the manual again.
Here's a direct quote:
"When you install a total memory capacity of 4GB or more, Windows
32-bit operating system may only recognize less than 3GB. We
recommend a maximum of 3GB system memory if you are using a
32-bit Windows operating system."
On 8/10/2011 11:58 AM, Pimpom wrote:
> Grinder wrote:
>> On 8/10/2011 7:04 AM, Pimpom wrote:
>>> I've long heard that a 32-bit OS can use only up to 3.25 GB
>>> system memory. This is the case with my own computer which has
>>> 4
>>> GB installed and TaskManager shows 3.25GB usable memory.
>>> However,
>>> while checking around for a new system, I read in some Asus
>>> motherboard manuals that if 4GB or more is installed, a 32-bit
>>> Windows OS may recognize less than 3 GB and they recommend
>>> installing a maximum of 3 GB.
>>>
>>> The usable memory size obviously does not drop below 3GB in
>>> all
>>> installations of 4GB and 32-bit Windows. So why the heads up
>>> from
>>> Asus? Can it happen under certain combinations of hardware
>>> and/or
>>> software?
>>
>> 32-bit operating systems, with some sort of Physical Address
>> Extension
>> (PAE), will never be able to fully utilize 4GB. Windows XP, by
>> default does not use PAE. It does look like you can enable it:
>>
>> http://msdn.microsoft.com/en-us/wind...dware/gg487503
>>
>> ...but my understanding it is not supported nor recommended by
>> Microsoft.
>
> Actually my question was not about being able to use 4GB, but
> about the possibility of being reduced to less than 3 (three) GB
> if 4GB or more is installed. That possibility is clearly stated
> by Asus in their manuals. I've just found the manual again.
> Here's a direct quote:
>
> "When you install a total memory capacity of 4GB or more, Windows
> 32-bit operating system may only recognize less than 3GB. We
> recommend a maximum of 3GB system memory if you are using a
> 32-bit Windows operating system."
>
>
4gB is the upper limit of RAM addressability in a 32-bit OS -- there aren't
enough address lines to do any more. The reason that a given system might
(will) be able to access less as general purpose RAM is that addresses are
used up for other things. In a modern system the biggest culprit is the
display controller. Have a video card with 512kB? Then that 512kB is
subtracted from your RAM. Have a golly gee wiz 1gB card? Then that 1gB is
subtracted. There are little bits of memory besides the video card and
there always have been but modern video cards aimed at gaming have so much
memory that the situation has gotten much worse quite suddenly.
> On 8/10/2011 11:58 AM, Pimpom wrote:
>> Grinder wrote:
>>> On 8/10/2011 7:04 AM, Pimpom wrote:
>>>> I've long heard that a 32-bit OS can use only up to 3.25 GB
>>>> system memory. This is the case with my own computer which has
>>>> 4
>>>> GB installed and TaskManager shows 3.25GB usable memory.
>>>> However,
>>>> while checking around for a new system, I read in some Asus
>>>> motherboard manuals that if 4GB or more is installed, a 32-bit
>>>> Windows OS may recognize less than 3 GB and they recommend
>>>> installing a maximum of 3 GB.
>>>>
>>>> The usable memory size obviously does not drop below 3GB in
>>>> all
>>>> installations of 4GB and 32-bit Windows. So why the heads up
>>>> from
>>>> Asus? Can it happen under certain combinations of hardware
>>>> and/or
>>>> software?
>>>
>>> 32-bit operating systems, with some sort of Physical Address
>>> Extension
>>> (PAE), will never be able to fully utilize 4GB. Windows XP, by
>>> default does not use PAE. It does look like you can enable it:
>>>
>>> http://msdn.microsoft.com/en-us/wind...dware/gg487503
>>>
>>> ...but my understanding it is not supported nor recommended by
>>> Microsoft.
>>
>> Actually my question was not about being able to use 4GB, but
>> about the possibility of being reduced to less than 3 (three) GB
>> if 4GB or more is installed. That possibility is clearly stated
>> by Asus in their manuals. I've just found the manual again.
>> Here's a direct quote:
>>
>> "When you install a total memory capacity of 4GB or more, Windows
>> 32-bit operating system may only recognize less than 3GB. We
>> recommend a maximum of 3GB system memory if you are using a
>> 32-bit Windows operating system."
>>
>>
> 4gB is the upper limit of RAM addressability in a 32-bit OS -- there
> aren't enough address lines to do any more. The reason that a given system
> might (will) be able to access less as general purpose RAM is that
> addresses are used up for other things. In a modern system the biggest
> culprit is the display controller. Have a video card with 512kB? Then that
> 512kB is subtracted from your RAM. Have a golly gee wiz 1gB card? Then
> that 1gB is subtracted. There are little bits of memory besides the video
> card and there always have been but modern video cards aimed at gaming
> have so much memory that the situation has gotten much worse quite
> suddenly.
>
> These may clarify:
>
> http://www.zdnet.com/blog/hardware/c...-memory-limit-
confusion/3124
>
> http://www.dansdata.com/askdan00015.htm
just for a heads up i just done an upgrade to asus m4a77t/usb3 motherboard
i could not install windows xp. i could install vista.
the winxp install when it tried to reboot after copying the instalation
files gave me some error about incorrect partition.
> John McGaw wrote:
>
>> On 8/10/2011 11:58 AM, Pimpom wrote:
>>> Grinder wrote:
>>>> On 8/10/2011 7:04 AM, Pimpom wrote:
>>>>> I've long heard that a 32-bit OS can use only up to 3.25 GB
>>>>> system memory. This is the case with my own computer which has
>>>>> 4
>>>>> GB installed and TaskManager shows 3.25GB usable memory.
>>>>> However,
>>>>> while checking around for a new system, I read in some Asus
>>>>> motherboard manuals that if 4GB or more is installed, a 32-bit
>>>>> Windows OS may recognize less than 3 GB and they recommend
>>>>> installing a maximum of 3 GB.
>>>>>
>>>>> The usable memory size obviously does not drop below 3GB in
>>>>> all
>>>>> installations of 4GB and 32-bit Windows. So why the heads up
>>>>> from
>>>>> Asus? Can it happen under certain combinations of hardware
>>>>> and/or
>>>>> software?
>>>>
>>>> 32-bit operating systems, with some sort of Physical Address
>>>> Extension
>>>> (PAE), will never be able to fully utilize 4GB. Windows XP, by
>>>> default does not use PAE. It does look like you can enable it:
>>>>
>>>> http://msdn.microsoft.com/en-us/wind...dware/gg487503
>>>>
>>>> ...but my understanding it is not supported nor recommended by
>>>> Microsoft.
>>>
>>> Actually my question was not about being able to use 4GB, but
>>> about the possibility of being reduced to less than 3 (three) GB
>>> if 4GB or more is installed. That possibility is clearly stated
>>> by Asus in their manuals. I've just found the manual again.
>>> Here's a direct quote:
>>>
>>> "When you install a total memory capacity of 4GB or more, Windows
>>> 32-bit operating system may only recognize less than 3GB. We
>>> recommend a maximum of 3GB system memory if you are using a
>>> 32-bit Windows operating system."
>>>
>>>
>> 4gB is the upper limit of RAM addressability in a 32-bit OS -- there
>> aren't enough address lines to do any more. The reason that a given
>> system might (will) be able to access less as general purpose RAM is that
>> addresses are used up for other things. In a modern system the biggest
>> culprit is the display controller. Have a video card with 512kB? Then
>> that 512kB is subtracted from your RAM. Have a golly gee wiz 1gB card?
>> Then that 1gB is subtracted. There are little bits of memory besides the
>> video card and there always have been but modern video cards aimed at
>> gaming have so much memory that the situation has gotten much worse quite
>> suddenly.
>>
>> These may clarify:
>>
>> http://www.zdnet.com/blog/hardware/c...-memory-limit-
> confusion/3124
>>
>> http://www.dansdata.com/askdan00015.htm
>
> just for a heads up i just done an upgrade to asus m4a77t/usb3 motherboard
> i could not install windows xp. i could install vista.
>
> the winxp install when it tried to reboot after copying the instalation
> files gave me some error about incorrect partition.
Owe i forgot to say i had some one ask me to reinstall their laptop
it had vista on it tried to install win xp again no go.
> Actually my question was not about being able to use 4GB, but
> about the possibility of being reduced to less than 3 (three) GB
> if 4GB or more is installed.
Yeah, sorry, sort of skimmed your message. Sorry about that.
Grinder wrote:
>> Actually my question was not about being able to use 4GB, but
>> about the possibility of being reduced to less than 3 (three) GB
>> if 4GB or more is installed.
>
> Yeah, sorry, sort of skimmed your message. Sorry about that.
1) The 4GB limit, is a "RAM license" limit.
2) The later service packs of WinXP x32, come with PAE enabled.
PAE must be enabled, to support the NoExecute (NX) feature.
PAE is not being enabled from a customer-centric viewpoint, to
enable large memory usage. It's for NX instead.
(It allows marking pages as not executable.)
3) As proof of this, try installing this RAMdisk.
This RAMDisk wouldn't be able to access memory above 4GB,
unless a PAE page table setup was in place.
The experiment I've done is:
1) Install 6GB of memory on P5E Deluxe.
2) Operating system used is WinXP Pro x32 SP3.
PAE is enabled by the OS (I didn't need to modify boot.ini).
3) When configuring the RAMDisk, it would install a 2GB
RAMDisk (using memory above 4GB). This can't be
accessed without PAE, as far as I know. And that
memory can't be used by programs. The reason the
RAMDisk can do it, is the RAMDisk lives in "driver land"
and the rules there differ.
The result of my experiment is, "3GB available" in the OS
itself, 2GB used by the RAMDisk, and 1GB remains inaccessible.
That means, my x32 computer was using *5GB* of RAM during the test
which lasted four days.
Even though the missing 1GB is probably lifted above the 4GB
mark, the RAMDisk won't use it.
Benchmarking the 2GB RAMDisk, is shown in this picture. I
wish I'd kept a picture of Task Manager, with everything
showing.
The memory license is for physical memory, and if you have
a swap file, then more than 4GB worth of programs can be
loaded. As long as the larger programs aren't resident, you
might still have some performance.
As a further experiment, I used the 2GB RAMDisk as a swap
file for the 3GB OS, and it was as smooth as silk, when
filled past the usual 3GB limit. The only problem is,
while that RAMDisk program is good, it still isn't
bulletproof. I no longer use that configuration,
because of detected anomalies (two problems in
four days testing). But if you wish to use that
RAMDisk for ordinary storage, it seems to be a lot
better than the last time I tested it. It crashed
pretty well immediately, the first time I ran it.
The recent versions are much better. Whoever wrote
that thing, knows a lot.
A 32 bit OS has a max address space of 4GB (to be precise 2^32=
4,294,967,296 )
Also the system itself needs part of this address space
For example if you have a video card with 1 GB of RAM then together with
address space need of other system hardware, only a maximum of about 2.8 GB
of adress space is left for your RAM
See you, Jan
"Pimpom" <pimpom@invalid.invalid> wrote in message
news:j1ts5d$b4c$1@news.albasani.net...
> I've long heard that a 32-bit OS can use only up to 3.25 GB system memory.
> This is the case with my own computer which has 4 GB installed and
> TaskManager shows 3.25GB usable memory. However, while checking around for
> a new system, I read in some Asus
> motherboard manuals that if 4GB or more is installed, a 32-bit Windows OS
> may recognize less than 3 GB and they recommend installing a maximum of 3
> GB.
>
> The usable memory size obviously does not drop below 3GB in all
> installations of 4GB and 32-bit Windows. So why the heads up from Asus?
> Can it happen under certain combinations of hardware and/or software?
>
John McGaw wrote:
> On 8/10/2011 11:58 AM, Pimpom wrote:
>> Grinder wrote:
>>> On 8/10/2011 7:04 AM, Pimpom wrote:
>>>> I've long heard that a 32-bit OS can use only up to 3.25 GB
>>>> system memory. This is the case with my own computer which
>>>> has
>>>> 4
>>>> GB installed and TaskManager shows 3.25GB usable memory.
>>>> However,
>>>> while checking around for a new system, I read in some Asus
>>>> motherboard manuals that if 4GB or more is installed, a
>>>> 32-bit
>>>> Windows OS may recognize less than 3 GB and they recommend
>>>> installing a maximum of 3 GB.
>>>>
>>>> The usable memory size obviously does not drop below 3GB in
>>>> all
>>>> installations of 4GB and 32-bit Windows. So why the heads up
>>>> from
>>>> Asus? Can it happen under certain combinations of hardware
>>>> and/or
>>>> software?
>>>
>>> 32-bit operating systems, with some sort of Physical Address
>>> Extension
>>> (PAE), will never be able to fully utilize 4GB. Windows XP,
>>> by
>>> default does not use PAE. It does look like you can enable
>>> it:
>>>
>>> http://msdn.microsoft.com/en-us/wind...dware/gg487503
>>>
>>> ...but my understanding it is not supported nor recommended
>>> by
>>> Microsoft.
>>
>> Actually my question was not about being able to use 4GB, but
>> about the possibility of being reduced to less than 3 (three)
>> GB
>> if 4GB or more is installed. That possibility is clearly
>> stated
>> by Asus in their manuals. I've just found the manual again.
>> Here's a direct quote:
>>
>> "When you install a total memory capacity of 4GB or more,
>> Windows
>> 32-bit operating system may only recognize less than 3GB. We
>> recommend a maximum of 3GB system memory if you are using a
>> 32-bit Windows operating system."
>>
>>
> 4gB is the upper limit of RAM addressability in a 32-bit OS --
> there
> aren't enough address lines to do any more. The reason that a
> given
> system might (will) be able to access less as general purpose
> RAM is
> that addresses are used up for other things. In a modern system
> the
> biggest culprit is the display controller. Have a video card
> with
> 512kB? Then that 512kB is subtracted from your RAM. Have a
> golly gee
> wiz 1gB card? Then that 1gB is subtracted. There are little
> bits of
> memory besides the video card and there always have been but
> modern
> video cards aimed at gaming have so much memory that the
> situation
> has gotten much worse quite suddenly.
> These may clarify:
>
> http://www.zdnet.com/blog/hardware/c...confusion/3124
>
> http://www.dansdata.com/askdan00015.htm
I haven't had time to read through everything in detail yet, but
a quick first glance, particularly at the second link, was very
helpful. I'll go through it in more detail later. Thanks.
Paul wrote:
> Grinder wrote:
>>> Actually my question was not about being able to use 4GB, but
>>> about the possibility of being reduced to less than 3 (three)
>>> GB
>>> if 4GB or more is installed.
>>
>> Yeah, sorry, sort of skimmed your message. Sorry about that.
>
> 1) The 4GB limit, is a "RAM license" limit.
> 2) The later service packs of WinXP x32, come with PAE enabled.
> PAE must be enabled, to support the NoExecute (NX) feature.
> PAE is not being enabled from a customer-centric viewpoint,
> to
> enable large memory usage. It's for NX instead.
> (It allows marking pages as not executable.)
> 3) As proof of this, try installing this RAMdisk.
>
>
> http://memory.dataram.com/products-a...ftware/ramdisk
>
> This RAMDisk wouldn't be able to access memory above 4GB,
> unless a PAE page table setup was in place.
>
> The experiment I've done is:
>
> 1) Install 6GB of memory on P5E Deluxe.
> 2) Operating system used is WinXP Pro x32 SP3.
> PAE is enabled by the OS (I didn't need to modify boot.ini).
> 3) When configuring the RAMDisk, it would install a 2GB
> RAMDisk (using memory above 4GB). This can't be
> accessed without PAE, as far as I know. And that
> memory can't be used by programs. The reason the
> RAMDisk can do it, is the RAMDisk lives in "driver land"
> and the rules there differ.
>
> The result of my experiment is, "3GB available" in the OS
> itself, 2GB used by the RAMDisk, and 1GB remains inaccessible.
>
> That means, my x32 computer was using *5GB* of RAM during the
> test
> which lasted four days.
>
> Even though the missing 1GB is probably lifted above the 4GB
> mark, the RAMDisk won't use it.
>
> Benchmarking the 2GB RAMDisk, is shown in this picture. I
> wish I'd kept a picture of Task Manager, with everything
> showing.
>
> http://img196.imageshack.us/img196/8...am2gbabove.gif
>
> Background info:
>
> http://en.wikipedia.org/wiki/Physical_Address_Extension
> http://en.wikipedia.org/wiki/3_GB_barrier
>
> The memory license is for physical memory, and if you have
> a swap file, then more than 4GB worth of programs can be
> loaded. As long as the larger programs aren't resident, you
> might still have some performance.
>
> As a further experiment, I used the 2GB RAMDisk as a swap
> file for the 3GB OS, and it was as smooth as silk, when
> filled past the usual 3GB limit. The only problem is,
> while that RAMDisk program is good, it still isn't
> bulletproof. I no longer use that configuration,
> because of detected anomalies (two problems in
> four days testing). But if you wish to use that
> RAMDisk for ordinary storage, it seems to be a lot
> better than the last time I tested it. It crashed
> pretty well immediately, the first time I ran it.
> The recent versions are much better. Whoever wrote
> that thing, knows a lot.
>
Ah, RAM disk. One of many things I miss about Amigas. RAM Disk
came integrated into the Amiga OS and I used it regularly. It was
utterly stable, size was dynamic and used whatever portion of
physical memory was unused by other processes.
Your experiments with large RAM amounts are interesting and I'll
definitely try them out when I get my new system.
Grinder wrote:
>> Actually my question was not about being able to use 4GB, but
>> about the possibility of being reduced to less than 3 (three)
>> GB
>> if 4GB or more is installed.
>
> Yeah, sorry, sort of skimmed your message. Sorry about that.
No problem. What I hate is when someone misses the point of a
carefully worded post and when it's pointed out, responds with
bluster and lame excuses.
More than 3GB with 32-bit OS 
Linear Mode
