Windows read 3gig instead of 4gig

Da_Banig

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I posted this under the XP selection as well. I bought a pair of 2gig RAMs. I read a lot about it and googled it as well, it helps me under how it works but I still can not get all 4gigs to work. I have a motherboard that supports 8gig, A cpu that has DEP enabled (PAE enable), enabled memory mapping (BIOS see all 4 gigs). I also tried the /PAE in boot.ini it does not work. I know that two gigs is reserved for apps and another 2 is reserved for windows. I am sure there's someway to make windows use all those 4gig RAMS. Please help me thanks
 

96Firebird

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You need the 64-bit version of Windows. It sounds like you may have already known that (since you mentioned PAE). If you're looking for a way to show 4GB with a 32-bit version of Windows, sorry can't help ya.
 
In 32 bit Windows operating systems, the total addressable space available is 4GB. If you installed total 4GB memory, the system will detect less than 4GB of total memory because of address space allocation for other critical functions, such as:

- System BIOS (including motherboard, add-on cards, etc..)
- Motherboards resources
- Memory mapped I/O
- Configuration for AGP/PCI-Ex/PCI
- Other memory allocations for PCI devices

Different onboard devices and different add-on cards (devices) will result of different total memory size. e.g. more PCI cards installed will require more memory resources, resulting of less memory free for other uses.

This limitation applies to most chipsets & Windows XP/Vista 32-bit version operating systems.

If you install a Windows operating system, if more than 3GB memory is required for your system, then the below conditions should be met:

1. The memory controller which supports memory swap functionality is used. The latest chipsets like Intel 975X, 955X, Nvidia NF4 SLI Intel Edition, Nvidia NF4 SLI X16, AMD K8 and newer architectures can support the memory swap function.

2. Windows XP Pro X64 Ed. (64-bit), Windows Vista 64, or other OS which can address more than 4GB memory.



Note: According to the latest Change Log published my Microsoft, Windows Vista 32bit SP1 will display the installed amount of RAM. This is a display change only.
 

dengamle

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Even with PAE and remapping you can't make it happen. This is a decision Microsoft made, to cut off access to the address space >4G . I believe they whine a bit about bad drivers and stuff.

A note: If you have DEP configured, the PAE kernel will automatically be loaded
 

Aragorn

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My, that was productive!

@OP, We still don't know if you are using a 32 or 64 bit OS. That is likely the key.
 

kcrush

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Basic answer is:

Win XP 32 bit, will always read 3GB max no matter how much is in there (I'm writing this on a Win XP32 machine that has 4GB of ram in it but only reads 3GB). No patches will be forthcoming because of addressing and OS limitations will cap its usable addressable RAM at 3GB.

Win XP64/Vista x64 bit should correctly show and use all 4GB as its limitation is 16TB.
 

dengamle

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As said, it is not an addressing limitation. Microsoft uses PAE to go beyond 4G. If they wanted to support more than 4GB in XP they could, and they did before SP2.

64-bit XP goes up to 128GB
 

zenmaster

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The max will be less than 4gb, but often much more than 3gb.
I see 3.67GB on my current XP box.

Must has to do with your chipset and add-on cards.
 

enewmen

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Just use Vista 64 and Remap the BIOS to get 4 or more gigs
A future version of 64bit windows can address 18446744 TERRABYTES.
For now, I think the 8 gigs is the (consumer) motherboard limit.
 

rodney_ws

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He won't be able to do that visually because I intend to gouge out his eyes since he's not using them and perform a lobotomy since he's not using his f'n brain.
 

dankcomp_danknuggets

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ya man, i had the same problem and i freaked out. i have 4 gigs of pc6400 (800mhz). xp only shows me like 2.5 gigs. but if u go into ur bios, ur system will show 4 gigs. u use 4 gigs, but xp juss says u only have 2.5 or 3, or whatever verion/build of windows u have. no worries, its juss a glitch i guess.
 

hassa

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You guess wrong - the answer previously stated WHY you don't see 4GB.
But here it is again in NON technical language
You have a 4L bucket - it CAN contain 4L of water if nothing else is in the bucket. This capacity is what the MB reports (physical capacity).
However, as stated some of the space is used for other things such as mapping for add ons etc... - in this example you put some rocks in the bottom of the bucket. Say they consume the equivilent of 0.5L of space.
You can now only put 3.5L of water in the bucket as 0.5L is used. This 3.5L is what windows is reporting...
If you want to carry your rocks AND 4L or more of water, then you need a 64bit OS (i.e. a bigger bucket)
 

halcyon

Splendid
Its interesting how many folks are unaware of the "you need a 64-bit OS for 4GB of RAM" but feel they need 4GB of RAM. TBH I don't really see over 3.5GB of RAM usage unless I'm doing some deep virtualization. Oh well, folks will learn just like we did.
 

hassa

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Also they don't know that their MB needs to support it too...

It is understandable though about people wanting 4GB - they know 2GB isn't enough for certain games (e.g. Supreme Commander) and know they need to pair it and therefore get 2x1GB plus 2x1GB instead of 2x1GB plus 2x512MB
 

night_wolf_in

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n give me 50cents each time. n i promise we will be rich very very soon
 
It's the price! RAM is so cheap, and everyone has always heard more is better. So now everyone who owns a computer can suddenly afford to buy tons of RAM whether they need it, or their PC can even use it or not.

"Darn my old PC is slow with these new games, lets see now, a new video card is $350. Hell fire, I can buy 2 more gigs of memory for $60! I am going to buy more memory instead! If more memory is good, then a ton more memory has got to be even better!"
 

WazzaUK

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Why???? 4gb is the max addressable memory addressable while running in 32bits....... As explained above......
 

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