Windows XP 32bit and 4Gb Ram

[DarphB]

I have read tons of articles with answers going both ways...
Is there a way to get windows XP Pro to see and utilize 4gb of Ram.
I just had Karaktu (some of you know him) build me a nice dual Xeon 3.4 with 4gb ram, 3 x 250gb Hard drives in a stripe system..
And for the life of me, I cannot get it to use the 4gb.
In task manager, it see's only 2gb of ram. In system Info, it see's all 4gb.
I have tried the /3gb switch in the startup...

Ideas? Or cant it be done?

Thanks


******** UPDATE***********BELOW*************

Well, a Major update..
After giving up a long time ago.. I decided to give SuperMicro a call (The MFG) of my mainboard.
They had no idea. Other than the classic it just wont work. OR it could be a add on card issue.
Well, I got a OLD FireGL 1000 from Karaktu and installed it today.
Well, its I still cannot believe it. It was my ATI x850
With the FireGL installed, I have 3.6Gb of Ram.
Install the x850 and I have 2Gb.

Not sure if this is an ATI issue or not.. I am getting a 6800GT and will test with that later this week and keep you all up todate...

********9-13-06*******************

Well, after getting a 6800GT and installing it.
I now have 3.1Gb of ram..

Interesting, with an ATI x800 with 256Mb ram (PCIe), I have 2Gb of ram

With an old Firegl 1000 with 8mg ram (PCI), I have 3.7Gb of Ram

With an Nvidia 6800GT with 256Mb Ram (PCIe) I have almost 3.1Gb of ram.

I am running this on a SuperMicro x6dal-B2 Mainboard with 2 x 3.4Ghz Xeon's
Do I contact Supermicro and tell them they have an issue? or ATI? Or?????

 

[Nothinman]

XP Pro supports 4G of physical memory just fine.

The /3G switch is for virtual memory, it has no bearing at all on how much physical memory Windows sees.

 

[nweaver]

with those specs, why not go with a server OS?

 

[Nothinman]

with those specs, why not go with a server OS?

Probably because of the cost and I'd bet that he just wants to use it to play games.

 

[Atheus]

Originally posted by: Nothinman

with those specs, why not go with a server OS?

Probably because of the cost and I'd bet that he just wants to use it to play games.

Doesn't look like it to me, but hey, I've seen people suggest that things like Silicon Graphics workstations would be just great for gaming Anyway, 4G of RAM would be useless for games, nothing uses more than like 1.5G.

I think there's a 2G limit on XP home, but not pro, so I don't know why it won't work. You sure the motherboard supports it?

 

[jlbenedict]

There is something about a certain addressable memory range that is reserved, so thats why Windows XP (32 bit) will only see and use about 3.25 GB.

 

[Nothinman]

Doesn't look like it to me, but hey, I've seen people suggest that things like Silicon Graphics workstations would be just great for gaming Anyway, 4G of RAM would be useless for games, nothing uses more than like 1.5G.

When I get a new machine it'll probably have 3-4G of memory in it just because it's so cheap. Whether games use it or not it'll be used by the OS and other running processes.

I think there's a 2G limit on XP home, but not pro, so I don't know why it won't work. You sure the motherboard supports it?

If system info reports 4G the board should support it. Most boards will lose ~800M to PCI address space so I could understand him seeing 3.2G instead of 4G, but not 2G. Unless it's a bug in taskmgr or something.

There is something about a certain addressable memory range that is reserved, so thats why Windows XP (32 bit) will only see and use about 3.25 GB.

That's the PCI I/O address ranges. But that can usually be worked around with a PAE or 64-bit kernel.

 

[DarphB]

Actually, I am running Windows Server 2003 Eval at the moment. And it does see and use all of the ram.

I am not using it much for gaming.. Some gaming yes.. Not alot..
I do a lot of video work, and it uses alot of ram.

But but to the x32 windows xp.
I did load xp, and in system info, it would see 4gb. Taskman would only see 2, and only use 2.
I understand the 3.2 to 3.4gb (Loss of usable ram) I dont have an issue with that. I just want to see it use over 2gb.. And it wont...


What am I missing?

Thanks for the input!

 

[Lord Banshee]

I thought only WinXP 32-bit each application has a limit of 2GB usage? Is this not true?

This might help the more than 2GB not showing up problem http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

 

[Smilin]

Lord B..

Each app has 2GB of user-mode virtual address space available. This is virtual memory and has nothing to do with physical memory. PAE is related to physical memory but only applies to systems with >4GB.




What version of 2003 server is the eval?

 

[yurimxpxman]

Windows' 2GB (more or less) limit doesn't change from 32bit system to 32bit system. It's the limitation of the 32bit architecture itself. If you want to use more than 2GB of RAM, you're going to have to go with a 64bit OS, such as XP Pro 64 or a 64bit Linux distro.

The actual addressing limitation is 4GB, but about half of it is used by misc. things on the motherboard.

 

[bsobel]

The actual addressing limitation is 4GB, but about half of it is used by misc. things on the motherboard.

This is incorrect.

 

[DarphB]

Its an R2 eval.

I did try the /PAE also..

I have a spare Drive around. Maybe I will try this again, and get some screen shots for everyone..

With Windows 2003 32bit version, I get all 4gb. (minus overhead)
With Windows xp 32bit version, I get 2gb.. I will let you know how it turns out...

 

[DarphB]

Ok, here's the deal..

Total Physical Memory 4,096.00 MB
Available Physical Memory 1.80 GB <------ I dont get this?
Total Virtual Memory 3.00 GB
Available Virtual Memory 2.96 GB
Available Virtual Memory 2.96 GB
Page File Space 2.17 GB

I have tried the /3GB switch and the /PAE
I have a 256Mb swap file.

???????
I am really confused here....

 

[stash]

I am really confused here....

Yep.

Physical memory != virtual memory.

edit: not sure why only 1.8GB of physical memory is available though. I didn't see you post what version of XP you are running.

/3GB controls virtual memory, and /PAE is only valid with greater than 4GB of physical RAM.

 

[DarphB]

Windows XP Pro SP2

So I guess the ultimate question is still here...
Is it posible to get >3Gb of Physical Memory available?

This has been driving me crazy for weeks.

The system see's it.. Why isnt it using it?

 

[yurimxpxman]

Originally posted by: bsobel
This is incorrect.

Right you are. It's been a while since I've read up on the 64bit architecture, so I'm a little rusty. It's not allocated by the motherboard; it's allocated by the operating system:

64 Bit Wiki Says:

Some operating systems reserve portions of process address space for OS use, effectively reducing the total address space available for mapping memory for user programs. For instance, Windows XP DLLs and userland OS components are mapped into each process's address space, leaving only 2 to 3.8 GB (depending on the settings) address space available, even if the computer has 4 GB of RAM. This restriction is not present in 64-bit Windows.

 

[Nothinman]

Right you are. It's been a while since I've read up on the 64bit architecture, so I'm a little rusty. It's not allocated by the motherboard; it's allocated by the operating system:

It has nothing to do with 64-bit vs 32-bit, unless I'm reading it wrong the part of the wiki you posted is completely wrong. The motherboard has to reserve addresses for all of it's hardware, usually this is around 500M-800M worth of addresses and since you only have 4G worth of addresses on a 32-bit system you only get ~3G of addressable memory. If you run a 64-bit kernel or a 32-bit one with PAE enabled you have a lot more addresses to work with and can thus address all 4G of memory and all of the motherboard resources.

Completely seperate from physical memory addressing is the virtual memory addressing and again on a 32-bit system you only have 4G so the kernel has to reserve some for itself (technically it doesn't, but the performance hit of doing a 4G/4G split is too high for most people) and in Windows this is 2G by default. If you boot with the /3G switch it'll take it down to 1G and give 3G to processes, but only if processes are marked as "3G aware". And the wiki described that wrong too, the 2G reserved for the kernel is just that, for the kernel not for XP DLLs or anything else in userland.

 

[DarphB]

Well, I cant say I am sure I know what you are saying..
Maybe more info is needed..
here is the Motherboard I am using:

Link to Motherboard

 

[Smilin]

Originally posted by: DarphB
Ok, here's the deal..

Total Physical Memory 4,096.00 MB
Available Physical Memory 1.80 GB <------ I dont get this?
Total Virtual Memory 3.00 GB
Available Virtual Memory 2.96 GB
Available Virtual Memory 2.96 GB
Page File Space 2.17 GB

I have tried the /3GB switch and the /PAE
I have a 256Mb swap file.

???????
I am really confused here....

Darph, if this is the output from MSInfo32 then your machine is already seeing 4GB of memory. It just happens to be using 2.2GB of it.

What is in the "Physical Memory (K)" section of the performance tab in task manager?

Total: ?
Available: ?
System Cache: ?

 

[Smilin]

also, can we please make this official for the duration of the thread to avoid any further unnecessary churn.


/3GB is for shifting the dividing address between user mode and kernel mode such that user mode address space is 3GB and kernel is 1GB instead of 2 & 2.

This is not applicable to this discussion and should not be used here

/PAE allows the addressing of more than 4GB of physical memory. It is not needed for 4GB or less.

This is not applicable to this discussion and should not be used here


Thanks!

 

[DarphB]

Total is 2Gb
Available 1.8
System cache I dont know off hand

 

[Smilin]

Originally posted by: DarphB
Total is 2Gb
Available 1.8
System cache I dont know off hand

So MSConfig tells you total 4, avail 1.8. While task manager tells you total 2, avail 1.8?

It's been a looooong time but I worked a case on this once. I believe those two apps use different calls to come up with the numbers. One of them reads directly from bios if I remember right.

Lemme dig for a bit on this. You might be seeing a problem reporting the memory rather than windows not being able to use it.

 

[Smilin]

more info (but no solution):


1) Why does MSINFO32 report the correct amount of RAM, 4GB
Ans: msinfo gets it's value by summing the size of each dimm

2) Why does task manager report lesser available RAM of 3538412K (3.37GB)
Ans: The OS available physical memory is reported from bios (memory type 1). This
is the value we would expect, based on the the bios memory map. As a system, we
build our memory map from the bios/firmware. In the x86 case, we build the memory
map from the bios service int 15h function 0xe820. The values reported by task
manager appear to reflect this memory map. So we are reporting whatever the BIOS is
giving us


Your bios may not be reporting your RAM correctly

 

[DarphB]

That is some interesting info.. Thanks!!

Here is another kicker for ya.
Thinking, that it was just being reported wrong, I opened 5 IE windows, ran a Fairuse dvd to avi conversion, dvdcopy dvd to avi, DVD shrink, and 2 virtual servers with 768 ram each..
Guess what.. I ran out of RAM.. 2gb gone, with no more to give.. System came to a creaping hault.

So I dont think its a reporting issue...