32bit OS not recognising RAM greater than 4GB??

jhonrox

jhonrox

New Member
Hello all,
I've got a small question here and any replies would be wonderful!

I recently read that 32bit versions of XP & Vista, when provided with more than 4GB of RAM, will only show less than 4GB in the specifications.

I'm now running 32bit XP Professional with 4GB RAM but the System Properties box says I've got just 3.25GB. My question is - does it mean only 3.25GB is used? Or does it mean all 4GB is used, but it just displays 3.25GB for some wierd reason?

Thanks!
 
All of it is being used, but it is used to Map other I/O device, IGP memory, Internal Stuff. Etc.

Between 2.75-3.25 is the max amount of memory a 32 bit OS can support.

But the 4Gb is still there, just being used elsewhere, and It will not be used as the other 3.25 RAM is used. The other .75 will not be used during gaming, web surfing, programming, etc.
 
ComputerGuru64x2 said:
All of it is being used, but it is used to Map other I/O device, IGP memory, Internal Stuff. Etc.

Between 2.75-3.25 is the max amount of memory a 32 bit OS can support.

But the 4Gb is still there, just being used elsewhere, and It will not be used as the other 3.25 RAM is used. The other .75 will not be used during gaming, web surfing, programming, etc.
Click to expand...

The whole 4GB address space is used, not the missing ram. That is just wasted. Can we agree on that?
 
But it is wasted (the issue is ram vs address space). I don't recall what that article says. I read it once, and it was not very good.
 
tyttebøvs said:
But it is wasted (the issue is ram vs address space). I don't recall what that article says. I read it once, and it was not very good.
Click to expand...

The article is fine, the issue is complicated which makes explaining it complicated. Also, whatever RAM is not addressed is not accessible by a 32-bit OS so technically it is wasted on a 32bit system. That said, if you have 4GB, why not get a 64-bit OS?
 
You dont understand, it isn't being wasted when it is the max amount that can be used.

Thats like saying your wasting food by not eating it when your full. Instead of eating it, you get it to go, and eat it somewhere else.
 
The article is not that fine. the author stumbles on what is what. Edit: The article I talk about here is the codinghorror one.

If 4GB is installed and 3.25 shows up then the rest of it is just wasted. Wasted as in sitting there doing nothing.
 
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ComputerGuru64x2 said:
You dont understand, it isn't being wasted when it is the max amount that can be used.

Thats like saying your wasting food by not eating it when your full. Instead of eating it, you get it to go, and eat it somewhere else.
Click to expand...

4GB is the max addressing space. If you have 4GB of RAM then all of it cannot be addressed because many other things are using that address space. If only 3.25GB of your RAM is addressed then the remaining .75GB is unaccessible to the OS.
 
But it isn't being wasted because it is still being used. Just because it isn't being used by the OS doesn't mean it isn't being used.
 
tyttebøvs said:
The article is not that fine. the author stumbles on what is what.

If 4GB is installed and 3.25 shows up then the rest of it is just wasted. Wasted as in sitting there doing nothing.
Click to expand...

Do you understand the difference between RAM and the Address Space?
 
ComputerGuru64x2 said:
But it isn't being wasted because it is still being used. Just because it isn't being used by the OS doesn't mean it isn't being used.
Click to expand...

It can't be accessed at all, it isn't addressed. It's like having a computer on a network with no IP address, it can't be accessed.
 
Microsoft Windows XP Professional, designed as a 32-bit OS, supports an address range of up to 4 GB for virtual memory addresses and up to 4 GB for physical memory addresses. Because the physical memory addresses are sub-divided to manage both the computer’s PCI memory address range (also known as MMIO) and RAM, the amount of available RAM is always less than 4 GB. The memory addresses starting down from 4 GB are used for things like the BIOS, IO cards, networking, PCI hubs, bus bridges, PCI-Express, and video/graphics cards. The BIOS takes up about 512 KB starting from the very top address. Then each of the other items mentioned are allocated address ranges below the BIOS range. The largest block of addresses is allocated for today’s high performance graphics cards which need addresses for at least the amount of memory on the graphics card. The net result is that a high performance x86-based computer may allocate 512 MB to more than 1 GB for the PCI memory address range before any RAM (physical user memory) addresses are allocated. RAM starts from address 0. The BIOS allocates RAM from 0 up to the bottom of the PCI memory addresses mentioned above, typically limiting available RAM to between 3 GB and 3.4 GB.
 
ComputerGuru64x2 said:
Microsoft Windows XP Professional, designed as a 32-bit OS, supports an address range of up to 4 GB for virtual memory addresses and up to 4 GB for physical memory addresses. Because the physical memory addresses are sub-divided to manage both the computer’s PCI memory address range (also known as MMIO) and RAM, the amount of available RAM is always less than 4 GB. The memory addresses starting down from 4 GB are used for things like the BIOS, IO cards, networking, PCI hubs, bus bridges, PCI-Express, and video/graphics cards. The BIOS takes up about 512 KB starting from the very top address. Then each of the other items mentioned are allocated address ranges below the BIOS range. The largest block of addresses is allocated for today’s high performance graphics cards which need addresses for at least the amount of memory on the graphics card. The net result is that a high performance x86-based computer may allocate 512 MB to more than 1 GB for the PCI memory address range before any RAM (physical user memory) addresses are allocated. RAM starts from address 0. The BIOS allocates RAM from 0 up to the bottom of the PCI memory addresses mentioned above, typically limiting available RAM to between 3 GB and 3.4 GB.
Click to expand...

Which proves my point. The extra RAM isn't available because it isn't addressed.
 
Which proves my point that it isn't wasted but it is still used. It is being used elsewhere.
It isn't like it is just sitting there.
 
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