4GB RAM and Windows XP

[WaiWai]

4GB RAM and Windows XP
I realise Windows XP (32-bit) supports up to 4GB RAM only.

However it says Windows XP needs to use some address space for your hardware, so only "4GB - address space reserved" will be usable in the operating system. That seems to mean some of your RAM are wasted due to the address space issues, aren't they? Thus


1. Since some of your RAM are occupied due to hardware address space issues, does it mean my RAM have been wasted (a waste of money to buy RAM that you can't use at all in any case)? If so, it seems to be wrong to think Windows XP can actually support up to 4GB RAM.


2. The above happens when I have 4 GB. Why doesn't it happen when I have 2 or 3 GB only? Doesn't our hardware still need to reserve memory space (or use some of my RAM)? Why am I able to use 100% of my RAM in the operating system when I have less RAM (but not when I have more)?


3. I wonder whether all these are display issues only. How much RAM being shown in the operating system doesn't change the fact that my hardware has to consume some of my RAM. Essentially they are using up the same amount of RAM in 2-3GB and 4GB cases. Buying 4GB doesn't make me waste more RAM than 2-3GB cases. Am I right?

 

[Nothinman]

That seems to mean some of your RAM are wasted due to the address space issues, aren't they? Thus

Yes and this has been discussed ad nauseum.

1. Since some of your RAM are occupied due to hardware address space issues, does it mean my RAM have been wasted (a waste of money to buy RAM that you can't use at all in any case)? If so, it seems to be wrong to think Windows XP can actually support up to 4GB RAM.

Pretty much.

2. The above happens when I have 4 GB. Why doesn't it happen when I have 2 or 3 GB only? Doesn't our hardware still need to reserve memory space (or use some of my RAM)? Why am I able to use 100% of my RAM in the operating system when I have less RAM (but not when I have more)?

Becaue the hardware addresses always start at the 4G mark and move down. It's the virtual addresses that are stolen not the physical ones and that's why you can remap the lost memory above the 4G mark and still use it if you have an OS that will let you.

3. I wonder whether all these are display issues only. How much RAM being shown in the operating system doesn't change the fact that my hardware has to consume some of my RAM. Essentially they are using up the same amount of RAM in 2-3GB and 4GB cases. Buying 4GB doesn't make me waste more RAM than 2-3GB cases. Am I right?

No, you're confused about virtual vs physical addresses and how they're used in this case.

 

[bwatson283]

This has been discussed to death on forums everywhere. The options are to run 64bit xp/vista or server, or just use less ram.

I have 4gb in my system because i was using xp64, but i just recently dove back down to 32bit for many reasons.

 

[WaiWai]

Originally posted by: bwatson283
This has been discussed to death on forums everywhere. The options are to run 64bit xp/vista or server, or just use less ram.

I have 4gb in my system because i was using xp64, but i just recently dove back down to 32bit for many reasons.

I know how to solve the 4GB RAM problem, that is to use 64-bit OS (which is not really a good solution so far). The best is to avoid buying 4GB.

I just don't understand some technical details of that case.

One more question. How can I know how much memory address will be occupied beforehand? I realise the memory addresses occupied varies depending on your hardware configuration, but how can I estimate the size of "memory holes".

 

[MagnusTheBrewer]

Originally posted by: WaiWai

Originally posted by: bwatson283
This has been discussed to death on forums everywhere. The options are to run 64bit xp/vista or server, or just use less ram.

I have 4gb in my system because i was using xp64, but i just recently dove back down to 32bit for many reasons.

I know how to solve the 4GB RAM problem, that is to use 64-bit OS (which is not really a good solution so far). The best is to avoid buying 4GB.

I just don't understand some technical details of that case.

One more question. How can I know how much memory address will be occupied beforehand? I realise the memory addresses occupied varies depending on your hardware configuration, but how can I estimate the size of "memory holes".

Basically, everything that has a driver will suck up memory addresses. You can look in Windows task manager to get a better idea or estimate but keep in mind there are processes that will make further inroads into addressable space as they are called.

 

[Peter]

It isn't drivers or processes what cuts into the address space available for RAM. It's the actual I/O hardware itself, the biggest chunks being graphics related.

 

[Nothinman]

You can look in Windows task manager to get a better idea or estimate but keep in mind there are processes that will make further inroads into addressable space as they are called.

Nope, each process has their own individual 4G address space.

 

[vailr]

Using 4x1GB memory, you get about 3.25 GB available for 32-bit Windows.
Memory needs to be installed in equal pairs to maintain "dual channel" compatibility.
So, for 32-bit OS's, probably most economical to use 2x1 GB + 2x512 Mb memory sticks.
Although with the recent drop in memory prices, probably almost equal end cost to just go with 4x1 GB sticks.

 

[lxskllr]

Are you sure you need that much memory? If you're not hitting your page file I wouldn't even worry about it.

 

[jonmcc33]

Originally posted by: vailr
Using 4x1GB memory, you get about 3.25 GB available for 32-bit Windows.
Memory needs to be installed in equal pairs to maintain "dual channel" compatibility.
So, for 32-bit OS's, probably most economical to use 2x1 GB + 2x512 Mb memory sticks.
Although with the recent drop in memory prices, probably almost equal end cost to just go with 4x1 GB sticks.

No, I have 3.5GB installed on my Asus PC-DL and it all shows up.

 

[lxskllr]

Originally posted by: jonmcc33

Originally posted by: vailr
Using 4x1GB memory, you get about 3.25 GB available for 32-bit Windows.
Memory needs to be installed in equal pairs to maintain "dual channel" compatibility.
So, for 32-bit OS's, probably most economical to use 2x1 GB + 2x512 Mb memory sticks.
Although with the recent drop in memory prices, probably almost equal end cost to just go with 4x1 GB sticks.

No, I have 3.5GB installed on my Asus PC-DL and it all shows up.

There's no firm number you can point to, every machine will be different. Of the 4gb I have installed, 3.07gb is available.