2.75 out of 4 Gigs Recognized?

[j6h10]

I just recently upgraded my computer to 4 gigs of OCZ DDr 800 SLI Ready (http://www.newegg.com/Product/Product.aspx?Item=N82E16820227269) and I set both sticks correctly and checked the BIOS but windows will only recognize 2.75 gigs? I have Windows XP 32-bit, but doesn't it recognize up to four? What should I do?

 

[Maziar]

Windows XP 32bit doenst recognize all 4GB of RAM,it recognizes max 3.2GB,if u want all of your RAM to be recognized then u have to install a 64bit OS.

 

[gamerk316]

Windows and other 32 bit systems can only use 2^32 (4GB) or RAM addresses. About 256MB is reserved by the memory controler, ports, and other motherboard functions. Your GFX card RAM (usually 512MB) takes up room as well, hence the famous 3.25GB (which is not always the case, a Geforce 2 MX will leave a PC with around 3.7GB free space, as its only a 64MB card). Sound cards and other hardware can eat up extra space too...

In practice, users are typically left with between 2.75 and 3.25 GB of usable address space, although installing something like a 4870X2 can leave you with a lot less... The only solution is to upgrade to a 64-bit OS.

 

[Scotteq]

In a computer all bytes in the memory system need a unique name. This is called an address. For example, if you have 2 GB of main memory, then there are 2147483648 bytes of RAM in your machine, each of which require an address for the operating system to communicate to it. To give these all an address you need 31 bits to do it. Now, if/when you have 32 bits, you can name 4 GB (2 bytes to the 32nd power = 4GB).

This is why the total addressable space available in a 32 bit OS is 4GB – the OS runs out of addresses and cannot communicate/locate any more bytes of memory because of that.

You may think ”Hey, 4GB of address space… 4GB of RAM… What’s the problem” The problem is that memory isn’t the only thing needing an address. If you install a total of 4GB worth of RAM, the system will detect/use/display 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. Again, this is a limitation of the Operating System not having enough address space to allocate to the system *and* the RAM. Not allocating address space to devices renders them inoperable. Not allocating addresses to RAM simply results in the unaddressed section not being used in an otherwise fully functional computer. Therefore the OS designers assign RAM last.


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

1. A 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. Installation of Windows XP Pro X64 Ed. (64-bit), Windows Vista 64, or other OS which can provide more than 4GB worth of address space.

 

[gamerk316]

Can we just stick Scotteq? His explanation is better than mine was...

 

[jonpaul37]

it would seem that you have a 1GB video card, would i be correct in saying so? or perhaps SLi/crossfire?

 

[gamerk316]

it would seem that you have a 1GB video card, would i be correct in saying so? or perhaps SLi/crossfire?

Could even be onboard sound. I get 2.75 with my Razer Barracuda and GX2, so I went to Vista 64 last week. It varies a bit, but usually its 2.75-3.25 GB you get max.

 

[XndeX]

To quote Scotteq;

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.

So when they going to make this a sticky???
Need to do this sooner or later.

Something tells me you got tired of trying to get this as a sticky

 

[Scotteq]

Something tells me you got tired of trying to get this as a sticky

Meh - Save it on a Word doc.. Cut/Paste/Post... Done.

 

[tokyotech]

I understand Scotteq's explanation of the 32 bit OS.

My question is whether I should upgrade to 64 bit XP, since I frequently run out of RAM when working on huge Photoshop files. I scanned through the OS section of this forum and noticed that most of the questions asked are how to fix 64 bit related problems. Not all your parts have 64 bit drivers and not all free anti-virus software has a 64 bit version. Do you think I will have these problems with my current setup (see footer)?

 

[gamerk316]

64-bit support has caught up. I'm running AVG free fine right now, and drivers haven't been a problem yet.

EDIT

64 bit support for vista is OK now, but XP64 is still lagging behind when it comes to drivers.

 

[Clatu]

Hi all, so if I understand it correctly, putting in 4gb of memory I'll get less than 4gb actually used on XP 32bit set-up. So, my system would still have more speed than staying w/2 gb and having 4gb installed (mem's cheap these days) will come in handy when I upgrade to say Windows 7 ?

 

[XndeX]

Hi all, so if I understand it correctly, putting in 4gb of memory I'll get less than 4gb actually used on XP 32bit set-up. So, my system would still have more speed than staying w/2 gb and having 4gb installed (mem's cheap these days) will come in handy when I upgrade to say Windows 7 ?

Simple answer yes.

Long answer,

Having 4 GB will allow you to load this in pairs.
I'm guessing you have 2 2GB chips?
Your Mother board will see all 4 GB.
Now depending on the OS as already stated a 32 bit OS will only see a maximum of 3 something GB depending on the configuration.
This includes Windows 7.
The only time you will see 4GB and above available for use is if you have a x64 OS.

So if you need to have all 4 GB of available memory you will need a x64 OS.

Later,

XndeX

 

[captaincharisma]

One thing I think should be mentioned is you are not going to be able to do an upgrade of a 64-bit version of windows from 32-bit. you will have to format the drive and install a fresh copy of windows

 

[Clatu]

Many Thanks for the info XndeX. I have a 4700C question but I'll post it in the correct forum.
Clatu

 

[Clatu]

One thing I think should be mentioned is you are not going to be able to do an upgrade of a 64-bit version of windows from 32-bit. you will have to format the drive and install a fresh copy of windows

Thanks ! Actually that's part of the prblm I'm having at the moment is a crashed HD but will post for help in appropriate forum.
Clatu