XP not reading all my RAM

Hi,

Xp x32 bit opertaing system will only identify a maximum of 4 gb of ram including onboard video which is why its only pick up 3gb of ram. the only way for it to pick up the additional ram would be to install the x64 bit version of windows.

Here is more information on the memory limitation
http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

If you're not onboard video like the previous poster suggests, it might be due to a limitation of the motherboard on how much ram it will support.

You might also find the following site helpful for future reference: http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

Chances are, if he is running 4GB or RAM, he is not running onboard video. The reason XP is only seeing 3GB is for drivers. XP reserves anything about 3GB for drivers. There is no way around this. By default, applications will only use up to 2GB of RAM also. You can change that with the /3GB switch in your system .ini file. To do so, righ-click on My Computer --> Properties --> Advanced tab --> Settings next to Startup and Recovery --> Edit button. Your .ini file will open for editing. At the end of the line below, you will add "/3GB" without the quotes.

Line will look similar to this:
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /3GB

See more about PAE and the /3GB switch here:
http://support.microsoft.com/kb/291988

Therefore as stated in order to get the most out of your machine you can upgrade to the x64 version of windows xp which will pick up the additional Gb you have

Upgrading to x64 has nothing to do with the 4GB of memory he has. His current setup will support it just fine.

This question has been asked many times before. Its a 32 bit OS limitation.

You may be confusing RAM memory size(in your case 4GB) and memory address allocation,
They are two totally different things.
Each component in your system needs memory address space including your ram, but cannot occupy the same address space together. The ram is last in line when it looks for address space allocated by XP. When all thats left is 3GB of address space, then all you see in XP is 3GB of ram. The rest,1GB of your ram, is not used and is dormant because it can't be addressed.

from an ASUS FAQ

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.

Whilst his current set up will support he wont be getting the full benefit of his set up

http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

You do not want to upgrade to x64 just for more RAM. Sparkmakers post elaborates more on what I was saying about Physical Address Extension (PAE). Read the Microsoft link I posted to learn more about your options. You will never see the full 4GB though.

Sorry but I wasn't elaborating on Physical Address Extension
Actually the 3GB PAE switch has nothing to do with the issue at hand-->why can't 4GB be seen<--He can already see 3GB.
The 3GB PAE switch is used to allow the OS to allocate 3GB to application resource rather than the standard 2GB allocation. In essence the application will have access , up to 3GB of memory allocation(if available) to run.

The confusion about an operating systems memory allocation space and RAM size is rampant .
Its a slight of hand by the retailers of computers, you never hear that  when 4GB is installed you will be wasting a portion of it, instead they tell you that the motherboard can install 4GB. That is true but only the BIOS will see it.

HSparkmaker hope you dont mind the followup but you seem to be the most informed ive seen on this subject is 4gb pointless then unless you use x64?

Yes, it is pointless to purchase 4GB of RAM in MOST situations. I say MOST situations, because I have 4GB of RAM and XP x86 is actually seeing 3.5GB of it. It all depends on your configuration (ie. PCI, PCIe, etc). And I do fully understand his question. I was just telling him that in fact his applications won't even be using more than 2GB of RAM (like you also stated) unless he uses the 3GB switch.

And about ONLY your BIOS being able to recognize the 4GB... not true:

http://members.cox.net/motocrazy/snap0065.jpg

Just about any program (including XP x86) will "recognize" the 4GB. XP x86 just cannot "use" the full 4GB.

I actually learned this stuff from Garycase,( the hard way) you should read some of his posts on the subject,
but the answer is not so straight forward. You are getting the benefit of at least 2.5 to 3.5 GB of RAM to use depending on how much of the address allocation is given to system resources, If you can live with the fact that some of your RAM is not being used, that is a good thing.
 The balance seems to be 2GB is the optimum for 32bit as the application resource allocates 2GB anyway to the running applications which is what really needs the ram.
The PAE switch mentioned earlier can stretch this resource but at the expense of perhaps starving some other  areas that need larger memory allocations.

Typically only drivers reserve upper memory space. Even if the drivers are not actually "using" the memory, they are reserving it. The Microsoft link I posted talks about all that and Physcal Address Extension (PAE). You could experiment with some of the things posted there, and if you do run into any driver problems, switch back.

CPUz uses the Panopsys hardware detection engine to get those specs from components on the motherboard which is a physical detection of the components. That is not the same as Windows reporting less than 4GB of addressable RAM. Once again , apples and oranges.

Sparkmaker is absolutely correct. If you want to see what is happening, open Device Manager, click on View, select Resources by Connection, and expand Memory. Then look at PCI bus entries. Those are address ranges allocated to devices which cannot be used to address RAM itself. Addresses are allocated to devices, not device drivers. For additional info, select Resources by Type and expand I/O section. That's a full list of reserved (or allocated) address ranges.

When 4GB is installed, an SLI system may only have about 2.75GB available while a lightly configured system will have around 3.5GB available.

Shared memory for integrated video also reduces the memory availabe to Windows regardless of amount of memory installed and whether OS is 32 bit or 64 bit.

I recommend that you not use the /pae switch or any of the other "fixes" you may find on the internet. They usually don't help and may cause stabilty problems.

If you have an address book with 4000 lines...
and 500 are reserved for the fire department, police, the plumber.
And you have 4000 friends you want to put in the book.
... only 3500 friends will fit.
The other 500 friends are still there but they won't have their address recorded in the book.

U. C. ??

.

Hi guys
thanks for all the feed back, well sounds like a storm in a tea cup for me - I am ur typical developer, I ma runnig VM Workstation with vm dev machines and thats why i went for as much ram as possible. I upgraded to VMWare workstation 6 cause its compatible with VISTA, so i was going to run Vista Business but ran into driver issues from the outset so i re-formated and stcuk xp on. My idea was to have vista as my main OS and just run VM machines running on the different platforms that i need.

Anyway apprently Micorosft will be releaseing the first service pack in June, If i run Vista will that do u think pick up all the RAM ?

thanks again

32-bit Vista has the same address table limitation as 32-bit XP.
The only ways around it are to use PAE which might cause driver problems or switch to a 64-bit OS which has a bigger address table.

Also Vista uses more memory just for the OS than XP so on the same computer XP will always have more memory available for apps than Vista does.

For you I suggest using 64-bit XP for the next year or two.
-
Let someone else work out all the Vista bugs for you and let the market create laptops that can handle more then 4Gb of memory.

.

ok, this has been rally interesting, last question on this, i am using VMWare with different dev machines,

as u know with each machine u allocate a certain amount of memory to it, by having 4 gigs can i utilize it all by using the vm machines as well?
also wat r the differences between 32 and 64 bit XP in terms of developing apps and stuff?

thanks allot
cheers

Good morning willcomp, I don't think of myself as being altruistic, but I didn't  even notice the points.
Your point though is well put as a lot of time and info has been given to this Q.

I didn't notice the points either but that doesn't matter much.
--
Thing is the origional question (XP not seeing all 4 GB) has been thoughly answered and a new question asked.
--
This Q should be closed out.
The new question needs opened as a new question.
--
.

@ PCBONEZ -- that was my point. Piggybacking on a 50 pointer.

As far as I know that is correct. Don't know why some are so chintzy. It's understandable for a limited member who's short on points.

Morning willcomp
Sorry if i did not add enough points to the question, i did not expect to spark off such a MASSIVE debate here. So if u feel there are not enough points then i will add some more is that ok?
I have been a member of EE for over 10 years, so my appologies if i have offended any of those that have helped with this question, after all it is all about the points eh?

thanks again :)

Well.. it's about helping people... yeah, and the points =).

I usually don't answer 50 point questions, especially from premium service members, unless they are Very simple.  It's not the points - I have plenty - it's the principle.

hey cool man, just glad i could get some help:)

i will in the future be far more aware of it, just never had a question that had so many posts by so many helpers


keep well guys

cheers