I'm currently running in windows XP 32bit mode with the PAE feature turned on. I have 8GB of Ram installed, but Windows only recognizes 3GB (which is to be expected). I am currently rendering some video, and Windows Task Manager is telling me that I am using 4.75GB of RAM (PF Usage). What is the explanation for this? I would expect the RAM usage to stop somewhere just above 3GB (I have two video cards (512 & 256).


Windows will use/see you pagefile.sys also as 'memory'. You page file is probably 4.80GB, so 4.80 + 3.25 = 8GB memory in total. It is not real memory of course, but it is used as memory.

This link describes how it works.


Video cards are irrelevant to how much RAM you have installed. Irrespective of the size of any page file, if you have 8GB installed;

  • Windows 32-bit will recognise upto 4GB RAM
  • Windows 64-bit will recognise 8GB+ RAM

Here is an interesting quote about Page files, which seems to make sense considering the size of your pagefile and that your running Windows XP 32-bit;

By default, XP creates a page file which is 1.5 times the amount of installed RAM and places it on the hard drive where XP is installed.

  • According to Wikipedia: "...although the theoretical memory limit of a 64-bit computer is about 16 exabytes (16 billion Gigabytes), Windows XP x64 is limited to 128 GB of physical memory and 16 terabytes of virtual memory". – martineau Nov 15 '12 at 11:25
  • I stand corrected, 16GB was probably enough - especially considering how much RAM cost in 2001, when XP was launched. To paraphrase a misquote of Bill Gates "16 Gigabytes ought to be enough for anybody". ;-) en.wikiquote.org/wiki/Bill_Gates – wonea Nov 15 '12 at 11:38
  • XP will probably finally be gone before 128 GB of physical memory becomes affordable, but I could be wrong. ;-) – martineau Nov 15 '12 at 11:46
  • You never know, there's always stalwarts with every edition of Windows, some deservedly so, for instance; Windows XP users passing over Vista, and 7 users passing over Windows 8 (controversial!). I doubt power users (those with high memory needs) will be sticking with XP. – wonea Nov 15 '12 at 11:54

Virtual memory and pagefile are technologies used by Windows to manage memory.

RAM and pagefile appears to the Windows as Virtual memory, so in your case, total amount of usable virtual memory would be 3GB(since 32x bit XP recognizes only ~3GB) + pagefile size (recommended size of PF is 1.5*RAM).

Virtual Memory on Wiki

Virtual memory

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.