I just installed more memory in my mom's laptop and anyway it has a total of 4gb's but only says 3.59gb's usable.. Is that normal or did I do something wrong?
Some PC's running Visat state they may take up to 4GB but will not use it all or it all won't be available? Like mine. It tells me I have to check with the company that makes it tro find out. Not sure which.
Is the graphics card intergrated? That could use some of the memory.
I found this....
"The cause for this is the so-called memory-mapped I/O (MMIO). Some devices need a dedicated space in memory. A typical example is a video card that utilizes the system memory. Now, you might object that your video card has its own memory and you didn’t install any additional devices that could occupy so much RAM. Well, for compatibility reasons Vista reserves memory for devices even if they don’t exist in your computer. That means that if you have 4GB RAM in your computer and Vista displays only 3.12 GB available memory, about 1GB is indeed not used by the OS. You might as well remove it. That is quite strange, isn’t it? I am not a system programmer, but for me that seems to be a design error, probably one that is very old."
Rest of article is here
It needs to be a 64-bit OS to recognize more memory.
It's a limitation of 32bit architecture...total mapped memory includes the video ram.....something in the order of 3 and a bit gig.
It's the number one reason why people switch to 64bit ...
On mine I have 64 bit and 8gb's of memory but I seem to remember something about this on a 32 bit machine, thanks guys..
32-bit Operating Systems (which includes most OSX, 32-bit *nix, and most Windows) have a hard limitation of about 4GB of addressable memory space.
Of the 4GB available to the OS, some of that memory is reserved for hardware communications, primarily the video card.
If you want to actively use 4GB or more RAM, you'll need to upgrade to a 64-bit operating system. There's a 64-bit release of Windows XP (which I don't recommend due to limited drivers). Vista also has 64-bit editions, but if you're going to buy a new Windows, get Windows 7. All retail editions of Win7 include both 32-bit and 64-bit versions - choose the 32-bit or 64-bit disc and get installin'!
You might have some old hardware that doesn't have 64-bit drivers. In my experience, these are typically add-in network cards, scanners, older printers (including fax/scan/print all-in-one doodads). Search for 64-bit drivers, and then determine whether you are willing to replace the devices with newer hardware.
There is also a chance that some older programs will not work with 64-bit Windows 7. I don't have a list, nor could I find a good list via Google.
I'll be making the 64-bit transition in the next couple of weeks, even though I don't have any computers with over 2GB RAM (yet).