Missing Memory

[Guest]

Up until today I was running 2GB (2 x 1GB matched pair) OCZ DDR2 667 memory
with no problems. I inserted another 2GB (2 x 1GB matched pair) Corsair DDR2
800 modules today.

The problem is my system only shows 2.6GB memory. I have tried all sorts of
combinations accross the 4 slots. With only 2 modules inserted it correctly
shows 2GB with both the old and new memory, however when I insert either 1 or
2 more modules it will only show 2.6.

Using 3 modules I tested the system slots leaving one empty each time, same
result 2.6

I have tested the system using an online sytem which indicated I had 4GB. I
have also dowloaded and ran Sisoft Sandra, which tells me I have 2.6GB
physical memory, but 4GB of chipset memory.

Now I'm really confused and would appreciate any help you can give

I have been told it has something to do with the BOOT.ini file and my BIOS
???????, my BIOS shows 4096MB memory.
--
Windows Vista Home Premium 32 bit
Asus P5W DH Delux
Intel QX6700 Quad Core
ATI HD2900 XT in Crossfire
4 GB DDR2

 

[Victek]

Up until today I was running 2GB (2 x 1GB matched pair) OCZ DDR2 667

memory
with no problems. I inserted another 2GB (2 x 1GB matched pair) Corsair
DDR2
800 modules today.

The problem is my system only shows 2.6GB memory. I have tried all sorts
of
combinations accross the 4 slots. With only 2 modules inserted it
correctly
shows 2GB with both the old and new memory, however when I insert either 1
or
2 more modules it will only show 2.6.

Using 3 modules I tested the system slots leaving one empty each time,
same
result 2.6

I have tested the system using an online sytem which indicated I had 4GB.
I
have also dowloaded and ran Sisoft Sandra, which tells me I have 2.6GB
physical memory, but 4GB of chipset memory.

Now I'm really confused and would appreciate any help you can give

I have been told it has something to do with the BOOT.ini file and my BIOS
???????, my BIOS shows 4096MB memory.
--
Windows Vista Home Premium 32 bit
Asus P5W DH Delux
Intel QX6700 Quad Core
ATI HD2900 XT in Crossfire
4 GB DDR2

32 bit Vista can use up to 4 GB, however some of that address space is
reserved. Usually Windows Vista shows 3.X GB when 4 GB is installed. It
doesn't imply that there's something wrong with your system. Below is a
link to a thread that discusses this at greater length.


http://groups.google.com/group/micr...8069c?lnk=st&q=&rnum=8&hl=en#1a629947adf8069c

 

[Michael]

You will not be able to use 4GB in Vista 32 bit versions. The 32 bit address
space allows for 4GB of memory, however portions of that space must be
reserved for physical devices and is not available to the operating system.
I think that most people with 4BG installed get a bit more than 3GB
available to Vista, there might be some tweaking in the BIOS that you could
do to get a bit more but not much.

You might consider just installing one more module (3GB) but be aware that
some memory configurations run slower if not set up in pairs, your manual
may comment on that.

Michael

 

[Victek]

You will not be able to use 4GB in Vista 32 bit versions. The 32 bit

address space allows for 4GB of memory, however portions of that space
must be reserved for physical devices and is not available to the
operating system. I think that most people with 4BG installed get a bit
more than 3GB available to Vista, there might be some tweaking in the BIOS
that you could do to get a bit more but not much.

You might consider just installing one more module (3GB) but be aware that
some memory configurations run slower if not set up in pairs, your manual
may comment on that.

Regarding the address space that is reserved for physical devices, why does
this not impact usable ram until the amount goes above 3 GB? Presumably the
devices need addresses regardless of the amount of ram in the system?

 

[Tom Lake]

Regarding the address space that is reserved for physical devices, why

does this not impact usable ram until the amount goes above 3 GB?
Presumably the devices need addresses regardless of the amount of ram in
the system?

Yes they do but since the total is less than 4GB, the reserved space is in
an area you
wouldn't see as RAM anyway.


|----------------------------------4 GB
Total-------------------------------|

With 4 GB:

|------------- 3 GB Available to OS-----------|---Reserved for hardware---|

With 3 GB:

|------------- 3 GB Available to OS-----------|---Reserved for hardware---|

With 2 GB:

|---2 GB Available to OS--|--Unused space---|---Reserved for hardware---|


So you can see that anything less than 3 GB is not affected by the reserved
area.

Some motherboards limit your RAM further.

Tom Lake

 

[Victek]

Yes they do but since the total is less than 4GB, the reserved space is
in an area you
wouldn't see as RAM anyway.

Thanks, I get it now.

 

[Lord Takyon]

Thanks, I get it now.

I did not realise this myself until recently. I had a few people asking why
their new 4 Gig machines did not show all RAM.