Memory Wrong in 64Bit Windows XP

Hi Paul

I don't know my motherboard model number. It is HP Compaq dc7600
Convertible Minitower. BIOS Version:Hewlett-Packard 786D1 v01.60 . Bios
version was upgraded yesterday. I did not found any "memory remap function"
can be modified.

by the way, where can I check the motherboard model number for you? I did
not see any number printed on motherbroad, but the HP guy told me that this
is Int 945G express

Alan.

"Paul" wrote:

> abcbalan wrote:
> > I have install 64bit XP. It only showed 3.25G RAM on computer properties,
> > but the actual physical ram is 5G (2x2G +2x512M).
> >
> > Symptom
> > - Bios shows 5G
> > - "My computer information - General" from Help and Support Center shows 5G
> >
> > - System properties only shows 3.25G RAM
> > - Task Manager->Performance only shows total physical memory=3407064
> >
> >
>
> What is the motherboard make and model number ?
>
> Does the BIOS have a "memory remap" function ? Have
> you tried changing it ?
>
> Paul
>

abcbalan wrote:
> Hi Paul
>
> I don't know my motherboard model number. It is HP Compaq dc7600
> Convertible Minitower. BIOS Version:Hewlett-Packard 786D1 v01.60 . Bios
> version was upgraded yesterday. I did not found any "memory remap function"
> can be modified.
>
> by the way, where can I check the motherboard model number for you? I did
> not see any number printed on motherbroad, but the HP guy told me that this
> is Int 945G express
>
> Alan.
>
> "Paul" wrote:
>
>> abcbalan wrote:
>>> I have install 64bit XP. It only showed 3.25G RAM on computer properties,
>>> but the actual physical ram is 5G (2x2G +2x512M).
>>>
>>> Symptom
>>> - Bios shows 5G
>>> - "My computer information - General" from Help and Support Center shows 5G
>>>
>>> - System properties only shows 3.25G RAM
>>> - Task Manager->Performance only shows total physical memory=3407064
>>>
>>>
>> What is the motherboard make and model number ?
>>
>> Does the BIOS have a "memory remap" function ? Have
>> you tried changing it ?
>>
>> Paul
>>

I'll take your word for it, that the chipset is 945G.

http://www.intel.com/Assets/PDF/datasheet/307502.pdf

See PDF page 207. The 945G supports a system address space of 4GB,
not 8GB like its more modern successors. There is no "remap" function
on the 945G.

You can install 4 x 2GB memory sticks in a 945G motherboard
that has four memory slots. But the chip cannot handle more
than 4GB, according to that Intel diagram on page 207. What
this means is -

1) Remove the 2x512MB sticks. They will never be used.
2) Keep the 2x2GB installed.
3) WinXP should continue to report the 3.25GB number
4) The remaining address space (0.75GB) is consumed to provide
address space for system busses and for the hardware connected
to them.

While your processor may support 64 bit, and 64 bit instructions
can be executed if you want, the WinXP X64 cannot correct the
hardware limitations of a 945G. You need a more modern motherboard,
to be able to install 5GB total memory, and actually see 5GB
reported in WinXP x64.

I'm really surprised the BIOS did not give error beeps, when
that much memory was installed... That is a testiment to the
cleverness of the BIOS designers, to handle the excess of
memory without complaint.

In the above Intel document, see PDF page 228, where it says

"Any memory in the system beyond 4 GB cannot be addressed
and should not be populated due to the additional loading
it places on the memory subsystem."

Only the first part of that sentence is really important to you
right now. The 2x512MB sticks are just wasting electricity and
are virtually invisible to WinXP x64.

For a picture of how a chipset with remapping handles this,
see PDF page 14 of this brief document. The function on page 14
is present in chipsets more modern than 945G.

http://dlsvr01.asus.com/pub/ASUS/mb/4GB_Rev1.pdf

HTH,
Paul

Paul wrote (in news:g95f1m$ogc$1@aioe.org):

> You can install 4 x 2GB memory sticks in a 945G motherboard
> that has four memory slots. But the chip cannot handle more
> than 4GB, according to that Intel diagram on page 207. What
> this means is -
>
> 1) Remove the 2x512MB sticks. They will never be used.
> 2) Keep the 2x2GB installed.
> 3) WinXP should continue to report the 3.25GB number

The question now is whether abcbalan installed the extra memory himself, or if
HP installed it even though it was pointless and charged extra.


--
Alec S.
news/alec->synetech/cjb/net