Windows 7 - Why does 4GB RAM only show as 3GB?

Asked By Qu0ll on 03-Apr-08 07:46 AM
I know that when using 32-bit Vista you can't expect to see all 4GB of
installed RAM but I was under the impression that you should see between 3.1
and 3.5GB.  My new Dell Precision laptop has 4GB RAM but only shows exactly
3GB.  The BIOS reports 4GB.

Is this unusual or indicative of a problem?

And loving it,

(Replace the "SixFour" with numbers to email me)

Alias replied on 03-Apr-08 07:51 AM
When you install SP1, you will see 4GB.

Bob Campbell replied on 03-Apr-08 07:58 AM
It's normal.   Different MBs support different amounts.   Some see as much
as 3.5 GB, some as little as 3GB, like yours.   If the laptop supports 64
bit and you need more than 3 GB, you need to install 64 bit Vista.
Qu0ll replied on 03-Apr-08 08:08 AM
What about Alias's comment that it would see 4GB under SP1?  Is that

And loving it,

(Replace the "SixFour" with numbers to email me)
John Barnes replied on 03-Apr-08 08:15 AM
It depends on what is installed on the computer.  Video cards with larger
amounts of memory will have smaller shown memory.  After SP1 you should see
all of it even though nothing has changed.
Steve Thackery replied on 03-Apr-08 08:18 AM
Yes.  It's a change Microsoft made, presumably due to so many customers
thinking there was a problem.  It *reports* 4G, but of course nothing has
changed under the hood - it still uses a little over 3G.

Qu0ll replied on 03-Apr-08 08:21 AM
The video card has 512MB of memory so perhaps that is a factor then.  Nice
to know though that all 4GB RAM will be accessible under SP1.  Thanks for
the confirmation.

And loving it,

(Replace the "SixFour" with numbers to email me)
Qu0ll replied on 03-Apr-08 08:27 AM
Ah, well ignore my comment in the other post then about it all being

And loving it,

(Replace the "SixFour" with numbers to email me)
Tom Lake replied on 03-Apr-08 08:41 AM
No, it WON'T be accessible.  It will be reported in the System Properties as 4 GB
but it still will not be used by the OS.

Tom Lake
Qu0ll replied on 03-Apr-08 08:50 AM
Yes, hence my other post.

Actually, I notice that my Server 2003 machine is 32-bit with 4GB and seems
to see and use all 4GB.  So it's not just a 32-bit thing - it must be
related to the nature of the OS itself.  Most of the explanations I've seen
for the low reporting are based on the "it's a 32-bit OS" argument.

And loving it,

(Replace the "SixFour" with numbers to email me)
Tim Slattery replied on 03-Apr-08 08:54 AM
It's a  BIG factor. See

No! SP1 will tell you that there's 4GB installed, but it won't use any
more of it than pre-SP1 systems did. The change is cosmetic only.

Tim Slattery
MS MVP(Shell/User)
ray replied on 03-Apr-08 10:48 AM
Asked and answered several times per week. Suggest you peruse the group.
Bill Yanaire replied on 03-Apr-08 11:05 AM
I am surprised you did not give the OP your Ubuntu talk.  What's wrong?  You
finally figured out that Ubuntu is a Pile of Junk?
Alias replied on 03-Apr-08 12:09 PM
How come you did not provide your expert opinion on the OP's problem
instead of bringing up Ubuntu?

ray replied on 03-Apr-08 12:27 PM
Nothing wrong. Why would I give a 'Ubuntu talk' if he did not ask about
Ubuntu? I still use primarily Ubuntu, Gentoo, Elive and Debian - because
they work.
Frank replied on 03-Apr-08 12:27 PM
Why is a lying linux loser like you in this ng, huh?
Tim Slattery replied on 03-Apr-08 12:33 PM
Hmm...I wonder. This page says
Server 2003 32 bit supports 4GB, and that claim is made for 32-bit XP
and Vista systems also. This one says
that 32-bit Server 2003 R2 Enterprise Edition supports up to 64GB,
means it would have to support PAE.

I don't know a lot about the server systems, but I suspect that if
you're not running the R2 Enterprise edition, it may be showing 4GB
but it's not using it anymore than Vista -  with or without SP1 -

And you're right that it's a 32-bit hardware thing. A 32-bit address
space translates to 4GB. That has to be used to access BIOS,  Video
RAM and a few other things. What's left over after those needs are
satisfied is used for system RAM.

Tim Slattery
MS MVP(Shell/User)
Bob Campbell replied on 03-Apr-08 12:46 PM
32 bit Windows Server versions DO support PAE, which gives 36 bits of
address space, which allows 64 GB of physical RAM.   But all other 32 bit
limitations still apply.

PAE is a hack whose time has finally passed.
Martin Burke replied on 03-Apr-08 12:52 PM
Ubuntu is getting better by the time 8.10 is out (few weeks) it should all
be fine, they even have a utility to run/install it on a Doze box with out
installing it !! All you have to do is click an icon on your xp/vista
desktop and Ubuntu is there.

The only thing wrong with Vista is its not compatable with older hardware,
annoying when you have to keep answering YES just to install / run
software. Very slow on anything with less than 4gig and only just about
works on 4gig, the "kernel" is based on 2003 so in theory should be stable,
its just the code on top thats flaky and makes it such a poor advert for

Linux   - Free not a Virus Spyware or Trojan in sight
Windowz - Expensive buggy  viruses spyware trojans  & SLOW
Vista OS- Vastly Inferior Sotware Try Another OS
Bob Campbell replied on 03-Apr-08 01:01 PM
Geez, ANOTHER version of Ubuntu?   The upgrade treadmill continues!

It installs on TV sets?   That's the only "doze box" I have, since I usually
fall asleep while watching it.

So you can install it without installing it?  Um, OK.

It's not?  Wow, you better tell that to my 4 year old ThinkPad T41 laptop
and my 10 year old HP LaserJet 4 printer!

No it's not.   Do you install software everyday?

No it's not.   I have it on a 2 GB P4 machine and it flies, plus the above
T41 laptop with 1 GB RAM.  Runs fine.

Congratulations, a whole paragraph of lies and FUD!
Frank replied on 03-Apr-08 01:01 PM
Got any more mis-information about Vista you lying linux troll!
ray replied on 03-Apr-08 01:40 PM
Yes - Just received notice last week that a nearby hospital is 'upgrading'
to vista. So they will be donating ten slightly used xp machines to the
local library where I volunteer. Among other things, we have four old
compaq 800mhz P3 machines (running Ubuntu) which will be replaced - and
set up with Ubuntu. They are a portion of our eleven public access
internet computers.
ray replied on 03-Apr-08 01:46 PM
Yes. They release one every six months - Linux is evolving. However, there
is not need to upgrade that often if you don't want to. 6.06 was a LTS
(Long Term Support) edition, and 8.04 (not 8.10 as referenced above) will
be also. Note also, that LTS on the server edition continues for a few
more years.

I manage, usually, to stay awake until Letterman's second commercial break!

You can install it on your MS installation, without having to install it
to disk in it's own partition. Of course, there is also the Live CD which
permits running it without install.

Evidently our local hospital thinks it doesn't. They plan to donate ten xp
machines to the local library as they 'upgrade' to vista.

Fairly frequently, actually.

Hmmmmm. And Gentoo runs quite nicely on my 1ghz VIA mini-itx. Actually,
Ubuntu is not doing too bad on the 800mhz P3's at the library, either.
Alias replied on 03-Apr-08 02:08 PM
Considering that I am not a "lying linux loser", your question is stupid.

Frank replied on 03-Apr-08 02:59 PM
Ken Blake, MVP replied on 03-Apr-08 03:25 PM
On Thu, 3 Apr 2008 22:46:41 +1100, "Qu0ll" <>

No, it's normal. There's no 3.1-3.5GB range.

All 32-bit versions of Windows (not just Vista) 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 not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but is
usually around 3.1GB. 3.0GB is slightly on the low side, but it's not
indicative of any sort of problem.

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.

Ken Blake, Microsoft MVP - Windows Desktop Experience
Please Reply to the Newsgroup
Little Billy replied on 03-Apr-08 06:49 PM
See if Dell has a patch, sometimes under properties it displays wrong. My
Sony was displaying the wrong processor which was fixed with the patch.
saeen replied on 12-Feb-09 03:09 AM
OK so 32-bit do not show the actual ram size but does it means that
system can only use the displayed ram amount?

Mike Torello replied on 12-Feb-09 03:39 AM
You've got it.
Chuck replied on 12-Feb-09 04:00 AM
In essence, yes, due to 32bit address space limitations and hardware.  Rom
address space and many video cards/chipsets  use RAM memory also, limiting
the amount of RAM available for general system & application use.

There are hardware methods that can utilize much greater amounts of RAM
memory for specific tasks, but these are not really implemented in either
32bit windows or most "IBM compatibles".

It's kind of amusing that Apple and HP implemented schemes that allowed
memory "pages" to be switched in and out of processor address space over
twenty years ago. (Apple II+, and HP Mini/Micro technical computers)

In the 1970's, HP used a scheme that allowed almost infinite memory to be
used by mapping memory segments in and out of the processors address space
on a memory "page" basis. The hardware support was based upon extensible
instructions that allowed the use of multiple words to describe a specific
memory location, with one bit in each word used as a flag, and if memory
serves, other bits pointing to the next memory location that contained
another part of the memory address. This might go on for several memory
locations to complete the address location information. Another trick of
HP's was to have internal and external instructions. The external machine
language instruction might be 16bits, and point to an internal instruction
of 24 bits. The internal instruction might also call a ROM routine.
+Bob+ replied on 12-Feb-09 08:20 AM
Most all computers with REAL operating systems did this. In addition,
they provided us with the ability to tune paging to maximize system
performance. MS-Windows swaps, it just does a very lousy job of it.
me replied on 12-Feb-09 08:28 AM
On Thu, 12 Feb 2009 02:39:20 -0600, Mike Torello

I have a related question.
I have a Compaq laptop with 2 gig of memory running Vista 32 bit. The
on-board video uses 256 meg of system memory. The laptop supports 4
gig of memory. Would the video use part of the 3 gig Vista uses or
would it use the 1 gig Vista doesn't use.
Tim Slattery replied on 12-Feb-09 09:30 AM
That's what it means. See
for an explanation.

Tim Slattery
MS MVP(Shell/User)
Tim Slattery replied on 12-Feb-09 09:33 AM
I assume you're talking about putting an extra 1GB into the computer
so that it now has 3GB. 32-bit Win Vista (and 32-bit XP and your
hardware) has a 4GB address space. It will assign addresses first to
your video RAM, BIOS and some other things. What's left over can be
used to access system RAM. Nearly always the amount of address space
that is preallocated in this way is less than 1GB, so you would be
able to use all 3GB of the RAM you installed.

Tim Slattery
MS MVP(Shell/User)
saeen replied on 12-Feb-09 09:48 AM
Thx all for support. :)

Mike Torello replied on 12-Feb-09 11:19 AM
Yes, the video would use part of the 3Gb of memory, just as it now
uses part of the 2Gb of memory.

Your system would "see" all 3Gb.
Poutnik replied on 13-Feb-09 04:53 PM
In article <>, says...

Do not mess physical address size, related to disk swapping,
and CPU address space, related to mapping memory in a out of it.

Swap files, or Linux swap partitions are pretty well sitting within CPU
address space.