Hi, before I launch into my question, please note that I've searched the web up and down and read my head wooly about this. I know about 32-bit WinXP's 4GB virtual memory limit, the 36-bit PAE fix, etc. I also know that it is common for XP to recognize only 3 to 3.5GB of 4GB physically installed. My problem: XP is only recognizing 2GB out of 4GB physically installed. That's at least a full GB that I'm getting jipped. Doesn't sit well at all. Is there something I can do, besides switching to a 64-bit OS, or is this outside of my control? The info: - WinXP SP3 32-Bit (legit, fresh installation) - Gigabyte GA-E7AUM-DS2H mobo (Geforce 9400 onboard gpu, 51MB physical RAM manually allocated) - 4GB (2x2GB) Patriot Viper PC2-6400 RAM - Intel Core2Duo 6400 (The mobo and RAM are new, CPU migrated from old PC, as did HDDs, PSU etc, all working fine) Now, the BIOS recognizes the full 4GB (3582MB, plus the 512MB allocated to the onboard geforce 9400 gpu, for 4094MB total). When I check the system properties in WinXP, however, it only reports 2GB and says 'Physical Address Extension' beneath it (I assume this means I have PAE enabled?). Considering that I have 512MB allocated to the onboard gpu, and allowing for a generous 512mb of other memory needs, I should still have 3GB reported. I have checked both DIMMs individually in the mobo, also checked all the different slots, and XP reports the expected 1.5GB every time. So, as far as I can see, DIMMs and slots are all fine. I also tried inserting both DIMMs but in different channels, even in this case XP only recognizes 2GB. I tried adding the /PAE extension to the boot.ini file (using Microsoft instructions, no less), but that made no difference at all after reboot. System properties reports 'Physical Address Extension' whether or not I add /PAE to the boot file... I've deleted it from the boot file since. All the memory timings I can see in the BIOS are set to auto or tied to the CPU, nothing funky going on there... Would someone help me out, please? Thank you!

PAE switch is only used if more than 4gig of ram installed. What is listed in system properties is just telling you the intel extensions are built in and nothing more. I assume you have no /MAXMEM switch in your boot.ini? What does xp report when you only have one memory stick installed? Same number for both sticks when placed in alone?

What is the model and brand of your motherboard? What are the specs on the RAM? What graphics card are you using?

Wanderer: as I wrote in the first post, perhaps unclearly, XP reports the correct RAM with only one stick installed. That is 1.5GB. The other 512MB are allocated to the onboard gpu. Both sticks work perfectly when used alone. You are correct about the /MAXMEM switch, I don't have it enabled. Should I? If so, can I just append it to the end of the ARC path like the /PAE switch? Thanks! Othehill: Read my first post to find out.

Apparently you have a lot of compnents that are being mapped to the 4GB of virtual address space (VAS). http://www.computing.net/howtos/sho...

I just installed Windows RC 7, 64-bit. It recognizes all my RAM, 4.00GB (3.00GB usable). YAY!