My Windows 7 laptop, 32bits, has 12GB in two memory slots, [ 4GB DDR3 SOdimm and one 8GB DDR3 SOdimm, click to see picture ].1

However, the system info, Task Manager and 3rd party software SIW indicate that just a fraction of that 12 GB is usable, or even seen.

Basic Info, native to Windows

Memory usage by SIW

Question: Why is that? And how do I make it so that all memory is usable? I hope this is clear, please ask me if it isn't.

Laptop is a Lenovo z-series, cpu is i3-4030u, 1.90Ghz


  • What kind of memory is it? What system is it installed it? What version and edition of Windows are you running?
    – Seth
    Apr 10, 2019 at 8:48
  • 3
    Possible duplicate of Why does Windows only show about 3.5 GB of my 4 GB of RAM?
    – gronostaj
    Apr 10, 2019 at 9:03
  • Yes it does look like a duplicate. Just read.
    – TiO
    Apr 10, 2019 at 9:07
  • Max addressable size in 32bit OS is 4 Gb. So OS and programs cannot use the memory above (and a lot below because some memory is occupied by shadowed ROM) for their code. But there exists some programs which can use this above memory as an extended data storage (they access this above memory by switching to another memory model where this memory is accessible) - for example, for to create virtual disk.
    – Akina
    Apr 10, 2019 at 9:31
  • Even if that older question was about Win XP, not Windows 7, like mine? Apr 10, 2019 at 10:02

1 Answer 1


TLDR: You will only be able to access 4GB combined of your memory due to using a 32bit windows environment.

This is a mixture of RAM & Video memory if you have a graphics card in your PC.

To utilize your memory you would need to install a 64bit operating system.

Why Can't 32-Bit windows access 4GB RAM: PC World

"Every byte of RAM requires its own address, and the processor limits the length of those addresses. A 32-bit processor uses addresses that are 32 bits long. There are only 4,294,967,296, or 4GB, possible 32-bit addresses.

Okay, so if the processor, and the operating system designed for that processor, can only handle 4GB, why can't your PC see that much?

Because not all of those addresses are available for RAM. There are other pieces of hardware inside your computer that need addresses, such as the PCI bus and the USB host adapter.

Your graphics card is probably the biggest address hog. Today's graphics adapters often contain a gigabyte or more of RAM, and every one of those bytes needs an address. To be fair, I doubt that many of those multi-gigabyte graphics cards are in 32-bit PCs, but even a 512mb video card will take a sizeable bite out of 4GB."

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