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4GB of memory and WinXP service pack 2

Last response: in Memory
May 9, 2006 10:32:52 PM

I have 4GB of corsair memory in an ASUS A8n32-SLI Deluxe with an AMD Athlon 64 X2 4200 + processor running WinXP pro service pack 2.

The "Hardware Memory Hole" should that be enabled or disabled to try and get my computer to see all of the memory?

With it disabled as the computer boots the memory check flashes 3040MB OK (Installed memory Size :4096MB. While System properties in WinXP reports 2.96 GB of RAM.

With it enabled. Which I believe is the setting to have my computer see all 4GB of my memory as the computer boots the memory check flashes 3984MB OK (Installed Memory Size : 4096MB) Which seems well and good as the bios has gone from reporting 3GB OK to 4GB OK. Well basically 4.

But when I boot to winxp System Properties reports 2.87 GB of RAM. So while the bios has gone from reporting
Installed Size 4096MB
Usable Size 3040MB

INstalled Size 4096MB
Usable Size 3984MB

Windows XP has dropped from 2.96 RAM to 2.87 RAM.
Not much of a change but I find it odd that windows would report less while the bios reports almost a full GB more avialable.

Anyone have any thoughts on this?

For now I'm going to disable it.
May 10, 2006 3:29:44 AM

Gah! ya beat me to it.

Summary of what I learned building my system:
Essentially, the Memory Hole settings in the BIOS allow for re-mapping of memory above the 4GB limit (current systems map device stuff here , starting @ 4GB and working backwards, hence you can't assign actual memory to where device interfaces/RAM shadows/etc. are already housed) but Windows XP 32-bit, being a 32-bit OS, is not able to use memory above 4GB address space without some ugly hacks (PAE) and even at that, with a hard limit on the actual address space, processes are still limited to using at very most 3 gigs of address space using another ugly hack (/3GB Windows boot switch, can be unstable!). Avoid that much memory unless you really need it and are willing to put up with the issues presented by a somewhat bleeding-edge arena of x64 OS's. While most stuff works, there's just enough that doesn't work quite right to make it annoying.

My $.02

NOTE: my info-rant was not meant to insult your intelligence kwalker, rather it was to inform others reading the thread as to what is going on with the memory hole and why it's needed.
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May 10, 2006 3:35:56 AM

no insult taken
May 10, 2006 1:40:26 PM

you need xp 64bit for that much RAM while running at 32bit you CPU cannot address that much RAM, running xp64 will allow your CPU to run 64bit code and therefore address far more than 4GB
May 10, 2006 5:12:10 PM

you need xp 64bit for that much RAM while running at 32bit you CPU cannot address that much RAM, running xp64 will allow your CPU to run 64bit code and therefore address far more than 4GB

Well, while that is true about 64-bit code (which should theoretically be capable of asddressing multi-terabytes of address space) even 32-bit apps, when compiled with a specific flag, can take advantage of running on a 64-bit system.

Normally, 32-bit programs and processes in Windows are currently limited to 2GB of space per process, while the OS gets 2GB of address space for itself (4GB total = 2^32). With these specially compiled 32-bit programs, when they are in a special environment (either 64-bit Windows or a 32-bit windows with the /3GB boot flag) the 32-bit process can use up to 4 GB of address space, the maximum afforded by their 32 bit memory addressing capabilities. A M$ KB article on the subject. Some programs with that flag compilation include many simulation suites, MatLAB, Photoshop CS2, Blender 3d, just to name a few.
September 27, 2008 10:00:36 AM

ive got almost the same hardware setup as the original poster, only ive got 3 G of ram.

ive got the memory hole enabled so all 3 gigs are showing fine on the system boot memory check but the system info in windows XP is showing only 1.48 gigs of memory.

anyone know how to fix this?