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View Full Version : I Thought Windows XP Pro could handle more memory


john19055
04-24-06, 11:01 AM
I thought with windows XP Pro it would support more then just 2.75gigs ,what
does the pro have that is useful from windows XP home.

-=DVS=-
04-24-06, 11:55 AM
Here you go full list .
Linky (http://www.winsupersite.com/showcase/windowsxp_home_pro.asp)

lightman
04-24-06, 01:24 PM
I thought with windows XP Pro it would support more then just 2.75gigs ,what
does the pro have that is useful from windows XP home.

No 32bit OS supports more than 4GB. Most support only 2.75-3.5 ...

Nutty
04-24-06, 06:37 PM
I believe XP can address 4GB, but this includes your page file also. So if your page file is 1GB, you can only address 3GB of physical ram.

-=DVS=-
04-24-06, 08:48 PM
This is interesting someone should try setting pagefile to 0 , and see if Windows displays whole 4 gigs.

Rakeesh
04-24-06, 09:15 PM
No 32bit OS supports more than 4GB. Most support only 2.75-3.5 ...

I believe XP can address 4GB, but this includes your page file also. So if your page file is 1GB, you can only address 3GB of physical ram.

You both are close. What is really going on is that 32-bit processors can only address up to 2^32 bytes of memory per clock cycle. The OS could go higher with some kernel tricks, but all > 4GB memory would be accessed slower, neverminding the fact that doing this in the first place would be downright messy from a programming perspective.

But RAM isn't the only memory that your CPU addresses. Your BIOS, your video card, your sound card, your network card, and pretty much every other device that resides on the ISA/PCI/AGP/PCI-express bus(es) holds memory that consumes parts of this address space. While you theoretically could have 4GB of ram, you aren't going to be able to use all of it because of this.

I would say that with pretty much all modern systems, if you ever want to go above 3GB realistically, you are going to need a 64-bit processor running a 64-bit OS.

The reason you in particular can't even reach 3GB is probably due to your SLI setup. Both of those video cards add up to a lot of memory. If you switch to a 64-bit OS, you'll be able to use all of the memory you have.

AthlonXP1800
04-24-06, 09:25 PM
This is interesting someone should try setting pagefile to 0 , and see if Windows displays whole 4 gigs.

Well I tried set pagefile to 0 and restarted PC but Windows still showed 3GB, it didnt worked. :(

Rakeesh
04-24-06, 09:27 PM
Thats why you use a 64-bit OS. (well, one reason anyways...) 2^64 = 16 ExoBytes maximum address space. You can fit a lot more than that 4GB in there.

jAkUp
04-24-06, 10:08 PM
I think if you add /PAE in the boot.ini file, you can get the full 4GB's...

john19055
04-24-06, 11:35 PM
I just have 3gigs put in but it only registers 2.75gig ,putting /PAE in the boot.ini file will make the Bios show the full 3gigs,what is /PAE ,how does that work .

AthlonXP1800
04-24-06, 11:57 PM
I think if you add /PAE in the boot.ini file, you can get the full 4GB's...

Tried that, didnt worked either.

|MaguS|
04-25-06, 12:01 AM
http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

a12ctic
04-25-06, 12:08 AM
no, the only change in pro is the blue loading bar during start up

$n][pErMan
04-25-06, 06:21 PM
no, the only change in pro is the blue loading bar during start up
lol.... you can acctually get that with Home too I believe...

Rakeesh
04-26-06, 01:20 AM
Tried that, didnt worked either.

http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

PAE is basically the kernel trick I was talking about. And in order to use > 4GB, you need to use windows server 2003, not XP pro, and the applications you use has to specifically support this feature.

I'll give you two guesses as to why 64-bit windows doesn't support this feature.

alex31
04-27-06, 11:53 AM
I have installed 3Go oh physical ram on an msi7123 (nforce4, athlon X2 3800) board and only 2.75G are seen by the bios.
At the os level (i use linux 64 bits which can adresse 64Go of ram) i see no more than the 2.75Go that bios shows, i think it's a motherboard/bios/chipset problem not an os one.

Alexandre

AthlonXP1800
04-27-06, 01:08 PM
I have installed 3Go oh physical ram on an msi7123 (nforce4, athlon X2 3800) board and only 2.75G are seen by the bios.
At the os level (i use linux 64 bits which can adresse 64Go of ram) i see no more than the 2.75Go that bios shows, i think it's a motherboard/bios/chipset problem not an os one.

Alexandre

Hmmm I think it the motherboard problem because MS-7123 does not listed on MSI website and anywhere on Internet, it probably an OEM motherboard with cutdown spec that are not available for retail. What system brand and model your PC?

MSI have 5 retail nForce4 chipset motherboards listed on the website:

NVIDIA nForce4 SLI X16 - K8N Diamond Plus (MS-7220-010)
NVIDIA nForce4 SLI - K8N SLI-FI (MS-7185-010) & K8N SLI-F (MS-7185-020)
NVIDIA nForce4 Ultra - K8N Neo4 Platinum (MS-7125-010)
NVIDIA nForce4 - K8N Neo4-F (MS-7125-060)

john19055
04-27-06, 05:36 PM
I have a Retail Gigabyte GA-K8N Pro SLI and have 3gigs installed,two 1gig sticks and two 512mb sticks but it only shows 2.75gigs in my bios.It looks like it would have to be something to do with the motherboard chipset or the cpu memory controlers because it just reads 2.75gigs before windows is even installed.

Rakeesh
04-27-06, 05:50 PM
I have installed 3Go oh physical ram on an msi7123 (nforce4, athlon X2 3800) board and only 2.75G are seen by the bios.
At the os level (i use linux 64 bits which can adresse 64Go of ram) i see no more than the 2.75Go that bios shows, i think it's a motherboard/bios/chipset problem not an os one.

Alexandre

That is a given, and a limitation in your case. However, not all motherboards have this limitation. If your motherboard is advertised as supporting 4GB, then it'll support 4GB.

john19055
04-27-06, 06:16 PM
It is advertised as to support 4 gigs. according to there site http://www.gigabyte-usa.com/MotherBoard/Products/Products_Spec_GA-K8N%20Pro-SLI.htm
According to there fact pages they say it is Due to standard PC architecture, a certain amount of memory is reserved for system usage and therefore the actual memory size is less than the stated amount. For example, 4GB of memory size will instead be shown as 3.xxGB memory during system startup.

Rakeesh
04-28-06, 01:18 AM
It is advertised as to support 4 gigs. according to there site http://www.gigabyte-usa.com/MotherBoard/Products/Products_Spec_GA-K8N%20Pro-SLI.htm
According to there fact pages they say it is Due to standard PC architecture, a certain amount of memory is reserved for system usage and therefore the actual memory size is less than the stated amount. For example, 4GB of memory size will instead be shown as 3.xxGB memory during system startup.

Where did you read this at? IIRC the PC architecture itself has supported 64GB for a while ever since the pentium pro came around, which was the first x86 to have 36-bit physical memory addressing (the virtual address is limited to the number of registers however, which is where the OS limitation eventually comes in.)

I think it is probably a limitation within your specific chipset architecture. Windows XP x64 itself is supposed to support up to 128GB of physical memory. I don't know what the limitations of the x86-64 linux kernel are.

alex31
05-03-06, 03:03 PM
Hmmm I think it the motherboard problem because MS-7123 does not listed on MSI website and anywhere on Internet, it probably an OEM motherboard with cutdown spec that are not available for retail. What system brand and model your PC?

it's a medion (http://www.medion.com/english/), and a model specifically built for an hypermarket store ...., and you are right about the motherboard.


I don't know what the limitations of the x86-64 linux kernel are.


Linux supports up to 4 GB (~2^32 bytes) of memory on 32-bit
architectures and 64 GB (~2^36 bytes) on x86 with PAE.
On 64-bit systems, Linux is supposed to support up to 16 EB (~2^64 bytes) of memory,
bot i have not tested that amount of ram :-)