4GB DDR memory not showing up in XP

#1
i have installed windows XP pro on an amd X2 computer, i have also put in 4GB of DDR in the system but windows in the system properties only sees 3gb

the bios sees 4gb. and im just wondering if there is a limit in XP or someway that i can get it to change to show the 4gb because i want to sell this system.

interestingly enough.
i will run a belarc on the system and it shows 3072 of total but then lists 4 banks of 1gb modules of ddr. odd

memtest also sees 4gb and i have run a total of 28 passes on it with no errors.

does anyone know how i can get windows XP to display 4GB DDR?
 

Heeter

Overclocked Like A Mother
#2
WindowsXP is designed to see only 4gigs of ram. Since it counts the pagefile as ram first (1/4 of your Ram, you case= 1gig) Then counts the rest of the ram sticks to complete the amount to 4gig. Disable your pagefile to list all 4 gigs.

Win 2003 does not have this problem as it is designed to work with 18gig or 20 gigs, or something like that.

Heeter
 
#4
to tell you the truth. its to sell it.

i had the extra memory around so i put it in and its fast as hell. but i want to ditch the system so i can move and to the people around here they think the bigger the number the better.
 
#5
Have you tried updating the bios on your mobo? It might be reporting to Windows wrong. Also, Windows XP Pro SP2 has a maximum of 4GB of ram I believe. Whereas XP 64bit and up do I think 16GB
 
#6
wow how rude of me. im sorry

thank you for the responce so quickly.

but i set the system to no paging file and it still shows the 3gb. odd.

any other ideas?
 

Perris Calderon

Administrator
Staff member
Political User
#9
ya, it's a bios and a compatibility problem.

there are a couple of things going on, there's a conflict casued by legacy 32-bit compatibility, and there are device issues

the processor only has 4 gigs of address space, it can't address more

memory and all device address spaces has to be mapped below 4GB. When 4GB of memory is installed in a machine there's a conlict between the physical memory and some devices that need address space.

for instance, Video memory has to be addressable by the processor...it's got to be mapped into some of the 4 gigs of processor address space even when the video card has it's own memory.,,this wouldn't be the case if the card also had it's own processor, but the bios would have to know or see that processor.

a card that carries 128MB of memory will need the same of processor address space.

most BIOS resolve this problem is by reserving a hole in memory address at the top of the 4GB range. it's called the “PCI Hole”, which exists below your 4GB and it ensures all 32-bit software can reach those addresses without an address confilct

The physical memory that's hidden isn't usable by the operating system software and therefore is “missing” from the system
 
Last edited:
#10
ok there is an option for a memory hole in the bois. if i set that to the 4gb or just over will i see it or is this a hopeless thign to get to work in XP pro????
 

Perris Calderon

Administrator
Staff member
Political User
#13
canadian_divx said:
is it possable to get XP to show this? does anyone know or is it just one of thoes windows things.
I'll attach a pdf for you to read later, I'm on a slow connection that won't upload right now, have a read when I post it

actually, I think this "fix" first appeared in sp2, so if you go to sp1 the os might see it.

I don't know though
 

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