XP not seeing 4 gb RAM

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Guest

I recently upgraded my machine from 2 to 4 gb of ram. My bios sees it all
(the motherboard supports 8) and I ran Sandra lite and it saw all 4 gb but
Windows says that I have 2.75 gb installed (by going under control pannel
then system). Is this a known problem (i have SP1 installed) or is it
something else? I would appreciate the help. Thanks.
 
xp home and pro only support upto 2gb, xp media center edition support upto
4gb. if you are running home or pro then you are out of luck
 
The memory that appears to be missing is actually allocated to hardware.. it
doesn't look good in the memory count, but your system is getting the full
benefit of all of the 4gb..
 
Cap said:
xp home and pro only support upto 2gb, xp media center edition support upto
4gb. if you are running home or pro then you are out of luck
Click to expand...

http://support.microsoft.com/kb/315335/en-us

APPLIES TO
• Microsoft Windows XP Professional Edition
• Microsoft Windows XP Home Edition

"The recommended RAM to run Windows XP is 128 megabytes (MB). The
minimum is 64 MB, and the maximum is 4 gigabytes"

Microsoft says you are incorrect. Mind you, I find XP painful to use
with less than 256MB, I hate to think what it would be like with only 64MB.

The "recommended" RAM seems ludicrous to me, but Microsoft knows their
product better than I. Maybe I should sell all the excess RAM I have
installed...

Sunny
 
Mike said:
The memory that appears to be missing is actually allocated to hardware..
Click to expand...

Could you elaborate on what you mean by that? And perhaps explain why
memory does not get "allocated to hardware" until you install more than 2GB?
it
doesn't look good in the memory count, but your system is getting the full
benefit of all of the 4gb..
Click to expand...

Is there a way for the end user to verify his system is getting the full
benefit of memory Windows doesn't acknowledge exists?

Sunny
 
Sunny

2gb installed is the cut off.. anything below that, and the system can't
afford to reserve for hardware other than integrated video..

Re. reporting, the BIOS should show all of the memory as it only reports on
what is physically installed, not how it is used in the system..
 
Mike said:
Sunny

2gb installed is the cut off.. anything below that, and the system can't
afford to reserve for hardware other than integrated video..

Re. reporting, the BIOS should show all of the memory as it only reports on
what is physically installed, not how it is used in the system..
Click to expand...

OK. That much I knew.

What I still don't understand is, what hardware *other* than integrated
video uses dedicated RAM?

Is there any way to see (in Windows) how the system is using RAM not
allocated as system memory?

When you install 4GB RAM, more than 1GB "disappears". That's a lot! It
seems reasonable to ask how the "missing" memory is being used, and what
benefit is provided as a result of removing it from system memory and
dedicating it to something else.

Sunny
 
Sunny

Your system allocates memory to various areas all of the time.. with 2gb or
less installed, it does it as required.. with over 2gb installed, it can
start to permanently allocate memory to the hardware.. this is NOT a bad
thing.. every function of the computer needs resource to work, whether you
can directly see it or not..

From a user standpoint, there would be no point is seeing what was happening
throughout the system.. the only 'easy to ascertain' functions are in RAM
available for programs, and video memory.. as long as BIOS recognises the
full amount, and assuming that the motherboard functions are all a-ok (BSODs
would show that they are not), then your system as a whole is benefiiting..
 
I have 3.0Gb of RAM installed and there is no indication any of it is
used/allocated anywhere except as RAM.

Rt-clicking My Computer > Properties show 3.00Gb of RAM.
 
I still think widows should show all your memory. When I do ctrl-alt-del and
go under performance. it has under physical memory:
total 2882528
available 2366448
system cache 408240

I think that total should read out around 4000000 (4 gb)
 
Mike said:
Sunny

Your system allocates memory to various areas all of the time.. with 2gb or
less installed, it does it as required.. with over 2gb installed, it can
start to permanently allocate memory to the hardware.. this is NOT a bad
thing.. every function of the computer needs resource to work, whether you
can directly see it or not..
Click to expand...

I specifically asked what hardware *other* than integrated video uses
dedicated RAM, and you responded "various areas".
From a user standpoint, there would be no point is seeing what was happening
throughout the system.. the only 'easy to ascertain' functions are in RAM
available for programs, and video memory.. as long as BIOS recognises the
full amount, and assuming that the motherboard functions are all a-ok (BSODs
would show that they are not), then your system as a whole is benefiiting..
Click to expand...

Not according to the Microsoft document at the URL Bob I posted:

"The physical address space is used to address more than just RAM. It is
also used to address all of the memory and some of the registers
presented by devices. Consequently, if a machine is configured with the
maximum amount of physical memory, some of that memory will be unusable
because some of the physical address space is mapped for other uses."

That explains why you can't tell me what other hardware uses dedicated
RAM - because there isn't any.

It also disproves your claim that "your system is getting the full
benefit of all of the 4gb". In fact the system is not using the
"missing" RAM at all, because it's *addresses* have been allocated
elsewhere, so the system cannot access the RAM.

Sunny



..provided a link to, you are dead wrong.the system is not benefiting
from the additional RAM because XP allocates memory and memory addresses
for communicating with devices. Any memory address used for device
communication may not be used for RAM access.
 
Sunny

By system, I was referring to system hardware, ie motherboard and its
functions.. the system as a whole does indeed benefit..
 
Jason said:
I still think widows should show all your memory. When I do ctrl-alt-del and
go under performance. it has under physical memory:
total 2882528
available 2366448
system cache 408240

I think that total should read out around 4000000 (4 gb)

:
Click to expand...
With 4GB of RAM plugged in, some cannot be addressed, because some of the
CPU's 4GB address space must be mapped to I/O registers. The person who
wrote the memory display code could have decided to display the amount of
RAM plugged in, but it seems more useful IMHO to display the amount of
RAM that can be addressed -- which is, AFAICT, what is shown.
 
so you are claiming that 1.25 GB of ram cannot be addressed????

That sounds like hogwash to me and hogs dont wash that fequently!

--
Kenny - www.ComputerBoom.com

"Any sufficiently advanced technology is indistinguishable from magic."

-Arthur C. Clarke
--
 
Thanks JJS.. you are normally so derogatory.. :-) .. (note: kfa).. the great
thing about technical terms is that they mean so many different things to so
many different people.. I await your contributions with interest.. I may
just learn something from you..
 
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