4 GB Memory in Windows.

slipd

slipd

slipd

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Can someone just remind me what the deal is with 4 GB of ram in Windows?

Vista uses all 4 GB doesn't it whilst XP only 'see's' a certain amount and can only use a certain amount – is that right?

Cheers,

SW.
 
Windows XP and Windows Vista 32-bit support an addressing range of 4GB and within this, the memory addresses are sub-divided to manage both the PCI memory address range also known as Memory Mapped I/O Device (MMIO) as well as the physical memory that you have installed in your system. This is the reason why Windows always reports less than 4GB even though you have 4GB of physical RAM installed in your system. Depending on your hardware configuration, even if you have 3GB of physical memory installed in your system, you may still see less than 3GB.

The PCI memory addresses, which are assigned from a top to bottom manner, are used for things like the BIOS, network cards, PCI-Express and graphics cards. The BIOS is first to take up around 512KB (Just as an example) starting from the very top address. Then the other devices as mentioned above are allocated an address range below that of the BIOS range. The largest chunk of addresses is used up by the graphics card which maps a large portion of the amount of memory it has access to, in the address space. The result of this is that the system may allocate 512MB to as much as 1GB maybe even more depending on your hardware configuration purely for the PCI memory addresses before any memory (Physical Memory) addresses have even been allocated.

Now, where as the PCI memory addresses which are assigned from a top to bottom manner, RAM is assigned the other way round from a bottom to top manner. In this case, RAM is allocated all the way up to the PCI memory addresses as mentioned above, limiting the available RAM to anywhere between 2GB to around 3.75GB.

It is all dependent on your hardware configuration and that's why it varies from one machine to the next. If you wish to utilize 4GB of RAM then you will have to be using a 64-bit Operating System weather that be Windows XP or Windows Vista.
 
FireWizard - I swear you post that every day! It really should be a sticky don't you think? Perhaps you could right a nice long sticky post with all the current FAQ's for windows as you seem extremely knowledgable. Maybe ask a mod..
 
jonislost said:
FireWizard - I swear you post that every day! It really should be a sticky don't you think? Perhaps you could right a nice long sticky post with all the current FAQ's for windows as you seem extremely knowledgable. Maybe ask a mod..
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Hello jonislost, I only post it when a question like this pops up. Though I can understand it gets tiresome. Sorry if it gets annoying after a while. :(:)
 
Fire Wizard said:
Hello jonislost, I only post it when a question like this pops up. Though I can understand it gets tiresome. Sorry if it gets annoying after a while. :(:)
Click to expand...

Hey man i meant no offence by it! As I said you always give great, clear inmformative advice. I was just thinking that using your knowledge perhaps you could make a general thread that tackles these common question that people have, and then get a mod to sticky it.

Keep up the good posting!
 
fothsn said:
Looks very strange seeing a 'z' in apologise :D:D
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Hello fothsn, I guess it does, hehe. :p

fothsn said:
I have 4Gb and running Vista Ultimate 64, but only 3006 is usable according to task manager.
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How much is Windows Vista reporting under "System Information"? If it is reporting exactly the same as above, you may have to go into the BIOS and enable a option called "Memory Remapping". :)
 
Will do just need to finish my work off, I can’t recall seeing any memory mapping features in my motherboard mind.

Here is what’s its showing now;


capturejp8.png





Ah just missed the system info bit, its showing 4Gb so I presume everything is all okay?


capturegg5.png
 
fothsn said:
Will do just need to finish my work off, I can’t recall seeing any memory mapping features in my motherboard mind.

Here is what’s its showing now;


capturejp8.png





Ah just missed the system info bit, its showing 4Gb so I presume everything is all okay?


capturegg5.png
Click to expand...
its only using 2.94gb of the 4gb.. u running 32bit?
 
Yes but 1.3Gb I dont think so, IIRC an old 2900XT I have used its same memory so it took 512Mb shared.
 
Hello fothsn, I am fairly sure that your graphics card isn't at fault here and causing Windows Vista to recognise 3GB of RAM instead of the full 4GB that you have installed, the problem lies elsewhere.

If there is a memory remapping option in the BIOS, make sure that it is enabled. If there isn't, have you got the latest BIOS for your motherboard? :)
 
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