total memory available is only 3.3GB with 4GB physical memory under windows 7 64 bit

I had 4GB physical memoryon the PC. With Windows vista 32 bit,
available memory is shown as 3.3GB. I asked and was told that only
under 64 bit windows, will the available memory be 4GB. When I
upgraded to windows 7, I chosed 64 bit, but the available memory shown
in the system is still 3.3 GB.

Why is this and is there a way to make the full 4GB available?

It's possible that my video card is using RAM instead of its own RAM.
If I install a video card with its own RAM, will the full 4GB be
available?

Thanks.

 

Little has changed in this respect in Windows 7.

Starting with Vista SP1, Windows now 'reports all of the installed RAM',
instead of only what is available to the OS.

However, nothing has changed as far as what is available to the OS. As
others have stated, with 4GB RAM installed, around 2.5 to 3.6GB will be
available, depending on the system.

Hope this helps.

And read the Microsoft KB @ http://support.microsoft.com/kb/929605/en-us

 

?:
You need to verify that the ram remapping above 4GB is enabled in
the bios to read the full system ram. Have a great day.

--
Dennis Pack
Win-7 Enterprise x64, Win-7 Professional x64.

__________ Information from ESET NOD32 Antivirus, version of virus signature database 4647 (20091129) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

 

32-bit Windows can address a maximum of 4GB. Graphics memory and system
BIOSes are included in the 4GB, so available addresses for RAM are less:
usually from about 3.5GB down to 2.7GB or so if a very large graphics
card is fitted.

64-bit Windows can address a much larger space, so provided the BIOS
allows the hardware addresses to be mapped above 4GB the full 4GB of RAM
- or more if fitted - can be addressed and used.

If you use onboard graphics which uses system RAM whatever is allocated
to graphics will not be available to applications. For 32-bit Windows it
would make no difference if 4GB was fitted, but would if there was less.
For 64-bit Windows separate physical graphics RAM is an advantage.

 

Three points here:

1. All 32-bit client versions of Windows (not just Vista/XP/7) have a
4GB address space (64-bit versions can use much more). 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. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.

2. In SP1 and SP2, Vista now reports all the RAM that's installed, not
just what you can access. I think that's a very poor thing Microsoft
did, since it misleads people. Nevertheless, you need to tell us what
level of Vista it was. Was SP1 or SP2 installed? If so, what I said
above doesn't matter and all 4GB should be reported.

3. So if it was SP1 or SP2, and 3.3GB was reported, then that was all
there was. You presumably have on-motherboard video support rather
than a separate video card, and the rest of the RAM was used for that.
But .7GB seems like a very strange number for on-motherboard video
support.

Your video card doesn't use System RAM. But again, if you have
on-motherboard video support instead of a video card, that's
presumably where the rest of RAM is being used, and whether Windows is
32-bit or 64-bit doesn't matter. (But again the amount seems very
strange)

If it weren't for that .7GB being so strange, I would say that was
almost definitely your issue and yes, installing a video card would
solve the problem. But with that strange number, I'm not sure.

 

On 29/11/2009 in message <> Ken

The OP said he had installed Win7-64 though.

 

The original post is confusing. 64 bit isn't a regular upgrade from 32 bit.
It would require a custom or clean install. It appears that the OP might
have just upgraded 32 bit Vista to 32 bit Windows 7 and thus the same amount
of ram is being reported.

Wayne

 

Like others said, the OP most likely needs to remap memory above the 4GB
barrier (in the BIOS).

John

 

I thought recent mobos did memory remapping by default. I know there is no
option in the BIOS of my A780GM-A Ultra to remap memory. With my recently
installed Vista 64, there is an indication that there is 3.75 GB of memory
(2x2 GB sticks) installed and 2.52 is available. The onboard video is using
256 MB and I assume other system devices and/or processes account for the
remainder of the difference between 3.75 and 2.52.

Wayne

 

If you have 4GB installed and if the onboard video is using 256MB then
the remaining 3.75GB should be available to your x64 operating system.
Where do you see that only 2.52GB is installed? I don't know what you
are running on your computer but unless you are running very hungry
applications I have a hard time believing that your processes are using
1.25GB of RAM!

This (lost RAM) is an addressing issue only, the hardware doesn't use
the lost RAM nor does the operating system. The hardware reserves
addresses at the top of the memory range just under the 4GB barrier so
that it can communicate directly with the processor, in turn the
reserved addresses are not available for the installed RAM so you cannot
see or use all the RAM (on 32-bit Windows), the RAM is without addresses
so it goes unused. The way around the problem is to remap the RAM
without addresses above the 4GB barrier and to use a 64-bit or PAE
capable operating system to access the memory above the 4GB barrier.

John

 

Not all machines do this automatic remapping, true that it is to be
expected on newer machines but don't bet the farm that all machines do it.

John

 

I'm running Vista x64 Ultimate and under System Tools there is a System Info
option. This isn't something I look at regularly but I did check it just
after I rebuilt this machine with a tri-core Phenom II and installed x64.

In there it shows Total Physical Memory and Available Physical Memory. This
is where I saw 2.52 GB available memory (not 2,52 installed) before posting
yesterday. This number changes and this AM it is showing 3.00 GB. The fact
that it changes led me to believe that the number has something to do with
what is running on the machine at the given time.

Wayne

 

What you say is correct. Available physical memory is the difference
between the total amount of RAM and what is in use at the time.

If you typically have that much available memory, you have more RAM
installed than you need--more than what you do with your computer can
make effective use of.

 

See attached for phyical and available memory as reported by Win7.

Thanks.

 

Attachement doesn't seemt to show up in previous post.

 

Don't know why attachment still doesn't show up.

Anyway, the following line is shown by win7 (Computer->Properties):

Installed Memory (RAM): 4.00GB (3.25GB usable).

Task Manager->Performance shows 3326MB as Total Physical memory.

This is 64 bit win 7 for sure.

Why only 3.25GB shown as usable? Under Vista 32 bit, it was the same.
Only 3.2 GB was shown as usable. I thought upgrading to 64 bit (it
was a clean install during "upgrading" of course) will help.

 

Something related to your motherboard. Could be a BIOS setting for
Memory Remap or a number of other things. You would need to check with
the manufacturer of your motherboard to find out the rest of the story.