windows xp ram limit?

Helix

got a new machine delivered yesterday and everything is going great with it apart from one little thing...

theres 4 gigs of ram in it, yet windows will only show 3.25gigs when all 4 1 gig sticks are in

on boot, all 4 ram locations are shown as being in use, and to troubleshoot it, i took one stick of the 4 out and booted up for each stick. every time, no matter what 3 sticks were in the machine, windows showed 3 gigs of ram.

so to me anyway, this means that each stick of ram is working fine

is it just a case that xp pro sp 2 has issues with displaying over 3.25gigs of ram on the computer properties page, or is there something gone astray?

the system itself is good to take 8 gigs of ram, so its definitely not that

cheers in advance

pete

Thomas_S_Hunterson

A 32 bit machine can only physically use a maximum of 4Gb, as to why it's maxing out at 3.25 under XP, i don't know.

Helix

its pro, and its a 64bit amd dual core machine

quaidox

it is xp home or professional you are using?? i'm pretty certain xp supports more than 3.25gb, but i can look it up for you in a mcsa ref manual...
just googled it there, and up to 4gb is supported

Helix

Helix wrote:

its pro, and its a 64bit amd dual core machine

no idea how that ended up above the post i was replying to

Reg_hurley

any chance its a Dell machine with intel motherboard?

CoNfOuNd

I think you need to turn off the windows pagefile for Windows XP to see over 3.25gb.

http://support.microsoft.com/default.aspx?scid=kb;en-us;308417

Helix

CoNfOuNd wrote:

I think you need to turn off the windows pagefile for Windows XP to see over 3.25gb.

http://support.microsoft.com/default.aspx?scid=kb;en-us;308417

excellent cheers

do i take from that, that the ram is there and in use but windows just isnt telling me its there, or that its only 3.25gigs actually being used until i knock the pagefile off? and in turning the pagefile off am i benefiting or will it be much of a muchness, bearing in mind theres not gonna be a pagefile in use?

im not entirely up to speed on this line of things

Helix

Reg_hurley wrote:

any chance its a Dell machine with intel motherboard?

nah its amd, havent had an intel board in a long while

DanGerMus

simple answer is a 32 bit OS will not ever use those 4gbs. it doesn't matter that your processor is 64Bit either (they all are these days). It cant, you need a 64bit one like XP(x64) or Vista(x64)

Helix

happygandalf wrote:

simple answer is a 32 bit OS will not ever use those 4gbs. it doesn't matter that your processor is 64Bit either (they all are these days). It cant, you need a 64bit one like XP(x64) or Vista(x64)

ah cool, so 3.25 is the limit for 32bit as we stand

thats grand, ill get xp64 so

thanks a million lads

Reg_hurley

Helix wrote:

nah its amd, havent had an intel board in a long while

Ok, I had an issue with dell/intel found this blog usefull:
http://blogs.conchango.com/jameshayes/archive/2006/10/26/Dell-D820-4GB-memory-problem-_2800_Part-3_2900_.aspx

This basically explained my situation:
"When the system boots and assigns I/O addresses this reduces the amount of RAM available to the system. This is not done by actually using that memory, but it is done by using the assignable memory addresses for other uses, thereby reducing the OS's and processor's available memory addressing space. About 3/4th of the last 1GB of addresses is utilized in your system for the PCIE bus addressing and the VRAM addressing, leaving you with about 3.2GB of usable addresses for RAM addressing."

So, the only advantage of having the 4GB of RAM rather than 3GB is you have 2X2GB sticks utilising Dual channel.

I think while I was researching my issue I came across a site that said amd had issued a bios update to get past the 3.25Gb limit.
And there was now an option to enable Memory Hole Remapping.

DanGerMus

Yeah i've had a look around and the basic jist of it is that XP wasn't desgined to use more than 3.2gb (ish), even though a 32 bit system technically can. And although you can actually get your system to see all the ram it wont use it. 64 bit os has been designed to support 4gb and more. Apparently the actual headroom for RAM in 32bit and 64bit systems is much much higher they just didnt design the OS to use it. Also i would suggest that in the long term Vista x64 might be the way to go as XP64 support is sparse and i just dont think anyone will be makin drivers for it.

Helix

vistas not gonna be an option for a good many years yet, as its a machine in a recording studio so new os's arent really the greatest of ideas til theyve got most of the teething problems ironed out and the drivers for external gear are healthy and bug free

i may just stick to xp pro at the moment, as theres not really any chance of me needing 4gigs of memory at the moment anyway

thanks for all the help

snappieT

I've been running vista for the last few months, and I'm happy enough, despite the occasional display driver lockup, it's pretty cool.