Actual memory available - how to get true reading?

[ChrisE]

I just purchased a custom pc w/ 4 gigs ram and WinXP SP2 on a P945 dual
processor.
Windows states 3 gigs physical and 2.5 available.

Are my memory demanding programs using the 4 gigs or only what WinXP
'sees' (3 gig limit)?

I have recently had a few blue screens plus Heap 'out of memory, free
up memory' error.

Chris

 

[Jim]

I just purchased a custom pc w/ 4 gigs ram and WinXP SP2 on a P945 dual
processor.
Windows states 3 gigs physical and 2.5 available.

Are my memory demanding programs using the 4 gigs or only what WinXP
'sees' (3 gig limit)?

I have recently had a few blue screens plus Heap 'out of memory, free
up memory' error.

Chris

If you use the /3GB switch in bootini, then XP will let your programs use up
to 3GB of user virtual memory. Otherwise, your programs can only use 2GB of
user virtual memory.
The amount of physical memory that your computer contains has no effect on
the amount of virtual memory. All that can happen is that more of your
virtual address space is located in physical memory.
Hence, your program may run faster because it swaps lots less.

Most multiprocessor systems let each processor access the entire amount of
physical memory that you have. Thus, unless your program is written to take
full advantage of a multi-processor cpu, whatever physical memory that the
other processor needs cannot be used by your program. I would suspect that
those messages are the result of your configuration.

I would also suspect that your programs would benefit from a full blown
64bit operating system (definitely not a 32bit operating system running on a
64bit processor).

Jim

 

[Tim Slattery]

This is a recurring question. XP cannot use 4GB of physical RAM.
Partly that's because the 4GB address space must be used to address
video RAM and memory and registers in other peripherals. But something
else is going on too. MVP Tom Porterfield posted this KB link:
http://support.microsoft.com/kb/888137

 

[Tim Slattery]

If you use the /3GB switch in bootini, then XP will let your programs use up
to 3GB of user virtual memory. Otherwise, your programs can only use 2GB of
user virtual memory.

Right, the switch controls allocation of the 4GB virtual memory space
that each process in XP gets. IT HAS NOTHING TO DO WITH PHYSICAL
RAM!!!!!

 

[ChrisE]

Thanks Jim and Tim - very helpful.

So did I buy too much ram when XP can only see/use 3 gig?

Also - should I increase virtual ram settings?

Chris

 

[Rock]

Thanks Jim and Tim - very helpful.

So did I buy too much ram when XP can only see/use 3 gig?

Also - should I increase virtual ram settings?

The amount of space to allocate to the page file depends on how much memory
is installed and what programs are run. As a general rule the more memory
in the system the less a page file is needed, but don't turn it off. XP
might complain. That oft heard rule of thumb to set the page file to 1.5 x
RAM is silly. That allocates too much for when there is plenty of RAM and
too little when there is only a small amount of RAM. See this article about
virtual memory in XP and setting the page file.

http://www.aumha.org/win5/a/xpvm.htm

 

[Guest]

I have lost memory , i have a total of 730mb of ram on an IBm T30 laptop.
But only one stick of ram is read. The second stick is gone. It use to be
all there before i reimaged my laptop. I had xp pro before and after. I
think it came up missing after i installed a patch or Office 2003 updates.
Thanks for any help.

655360 bytes total conventional memory
655360 bytes available to MS-DOS
627264 largest executable program size
1048576 bytes total contiguous extended memory
0 bytes available for contiguoius extended memory
941056 bytes available XMS memory
MS-DOS resident in high memory area

 

[Homer J. Simpson]

If you use the /3GB switch in bootini, then XP will let your programs use

Right, the switch controls allocation of the 4GB virtual memory space
that each process in XP gets. IT HAS NOTHING TO DO WITH PHYSICAL
RAM!!!!!

....not to mention anything about the fact that the switch does absolutely
NOTHING for programs that haven't been explicitely compiled with the
/LARGEADDRESSAWARE switch.

 

[Bob I]

That readout has absolutely nothing to do with the ram installed. Press
WinKey+Pause/Break key or R-click "My Computer", then properties to see
installed memory.

 

[Guest]

Bob
Thank you for your response. I am sorry i realize the DOS prompt box was
not wrong. However I did as you request and it is still the same. It only
shows 512mb of 796mb of ram. Thank you for any help you can give.

 

[Bob I]

A few things to consider
1. How much ram is actually installed? (you list a couple different values?)
2. How much does the BIOS report at boot up? (a stick has failed?)
3. How much is assigned to video? (no longer available to the system)

 

[Guest]

Dear Tim,

I came accross your answers about WinXP not being able to see all RAM on a
computer with 4 GB.

I have a similar problem and try to understand what it means and whether it
needs to be corrected.

1. On my PC, 2GB RAM is seen as 2GB by Windows, but 3GB is seen as 2.85GB,
and 4 GB is also seen as 2.85GB. Thus, it seems that 2.85 GB is the maximum
my Win XP can see ...

2. you mentionned that adjusment could be made in the boot.ini file (such as
includind a /3GB or a /4GB parameter, but I do not see where this change need
to be made. My boot.ini file reads as follows:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP
Professional" /noexecute=optin /fastdetect

3. I read in other forms that the pagefile needed do be adjusted. My page
file (with a present amount of RAM of 3 GB) is 2918 MB. I tried to modify
this by setting it to 1.5 the amount of RAM (as suggested in some forums),
but unsucessfully ( [1] if I try to put the lwoer limit at 4.5 GB, I get an
error message telling me that I cannot exeed 4096 MB; [2] if I enter 4096,
click on "set" and reboot, the computer still keeps the 2918 MB size limit...

My questions are:

- do I need to try to get the 4GB recognized by WinXP (any advantage in
thaht ?)
- conversely, is upgrading the computer to 4 GB RAM useless if it can only
read up to 2.85 GB (in which case, I'll keep it with 3GB)

I thank you for your comments.

Paul.