what is Windows XP's Max RAM limit? (home ed.)

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neocitron

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Apr 16, 2005
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what's Winxp home's ram limit? i currently have 1.5gigs.. 2x512 and 2x 256...
also... with that setup is it possible to run Dual channel... or does ram have to be equal size? it's the same make (OCZ.. same stock rated timings,. look all identical as well)
by the way.. CPUZ (latest version) says i'm running dual channel... somehow... but the sticks are of different size...
 
slamgoku said:
for dual channel. sorry dude.
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oh poo.. then CPUZ is wrong... it simply think's "even number of sticks in slots... so it must be dual channel!!.." it doesnt check if they're all the same size... stupid CPUZ...
oh well.. i'd much rather have 1.5 single ch.. then 1gig dual ch.
 
slamgoku said:
32 bits have a limit of 16 GB. So ur limited to 16 gb.
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What? No, no...

XP Home and Pro have a maximum addressable memory size of 4GB.
 
Searched "xp ram limit site:microsoft.com" and got:
Here's a list of how much RAM the various Windows versions and editions support (as of Nov 2004):

Windows NT 4.0: 4 GB
Windows 2000 Professional: 4 GB
Windows 2000 Standard Server: 4 GB
Windows 2000 Advanced Server: 8GB
Windows 2000 Datacenter Server: 32GB
Windows XP: 4 GB
Windows Server 2003 Web Edition: 2 GB
Windows Server 2003 Standard Edition: 4 GB
Windows Server 2003 Enterprise Edition: 32 GB
Windows Server 2003 Datacenter Edition: 64 GB
Click to expand...
 
To expand on lomn75's post:
Code: 
4.0:
Windows NT 4.0 [Workstn\srv\ent]:       4GB	

5.0:							
Windows 2000 Professional:              4GB
Windows 2000 Standard Server:           4GB
Windows 2000 Advanced Server:           8GB
Windows 2000 Datacenter Server:         32GB

5.1:
Windows XP [Home\Pro\XPE\MCE\TPC]:      4GB

5.2:					[x86]	[IA64]	[x64]
Windows XP                              -	16GB	128GB
Windows Server 2003 Web Edition:        2GB	-	-
Windows Server 2003 Standard Edition:   4GB	-	32GB
Windows Server 2003 Enterprise Edition: 32GB	1TB	1TB
Windows Server 2003 Datacenter Edition: 64GB 	1TB	1TB
 
32 bits have a limit of 16 GB. So ur limited to 16 gb.
Click to expand...
there are a few limitations. first physically what the processor can support via address, and data bus. the limitation in this mannor is 4GB, 32 bits data bus, and 32bits address bus. i will not go into PAE, but all modern processor support this feature (q.v. link posted). however, not all drivers, and core logics do support decoding of the mapped memory. motherboards/corelogic will be the next limitation. note, i have motherboard, and corelogic together for core logic may provide the interface to the memory, and have x support. however, not all motherboard manufacturers provide the support that the logic provides. most non-enterprise will only support up to 4GB-consult your documentation. last, is operating system management which has been posted.

remember this, since memory holds the mapped area for memory transfers and i/o, if you install 4GB, on a 32bit system, you will only have about 3.5GB usable memory to the system. still then an application can only use 2GB allocated to it. this is one reason for PAE, but really the main reason for 64bits. 32bits is very crowded.

http://msdn.microsoft.com/library/d...us/memory/base/physical_address_extension.asp
 
neocitron said:
i'd much rather have 1.5 single ch.. then 1gig dual ch.
Click to expand...

I wouldn't unless you use more than a gig of ram at a time, theirs no point in haveing 1.5 if you dont use 1 so why not double the bandwidth to your ram.
 
If I understand it correctly, assuming you have the memory in the correct slots, it will still run in dual channel. The memory has to be identical in terms of the channel, not overall. I ran, as a test, 2 sticks of Corsair XMS and 2 sticks of Kingston HyperX in the same system in dual channel.
 
most Windows apps can only address 2gigs per application.
Having more than 2gigs would be just for bragging rights.
 
WS6 said:
most Windows apps can only address 2gigs per application.
Having more than 2gigs would be just for bragging rights.
Click to expand...
Negative. Any *single process* is limited to 2GB, not all processes, and then OS has a 2GB limit as well. This means you can run multiple processes that consume more than 2GB.

Let's say you run 15 apps (AV, IM, Firewall, etc. + your user apps like internet, MS word, games) with 3GB on RAM. One of those is likely to be your primary memory consumer, lets assume it's a game.

So your first 14 programs take up say 150MB, the OS 150MB (just rough numbers for ease of demonstration). So that's about 300MB used, leaving 2.7GB. The last app, your main memory consumer, has 2.7GB, but it can only use 2GB of that. Lets assume it uses all 2GB, leaving ~700MB for 'other' use. This system is using 2.3GB of total memory.

 
As far as the dual channel goes, is it an Nforce2 board? Cos they can run dual channel if you have say 2x256 in 1&2 and a 512 in 3, but you dont have that anyway, just thought id point it out in case you have the other 256 around. Or, just rip the 256 out, dualchannel>>>extra256mb if youve already got a gig.
 
Phoenix86 said:
Negative. Any *single process* is limited to 2GB, not all processes, and then OS has a 2GB limit as well. This means you can run multiple processes that consume more than 2GB.
Click to expand...

that is what I said. IF you have a program that will use 2gigs, then more ram will help, but what app uses that much physical ram at any one time?
 
WS6 said:
that is what I said. IF you have a program that will use 2gigs, then more ram will help, but what app uses that much physical ram at any one time?
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More RAM will help with handeling the rest of the system's apps and the OS. Having more than 2GB is not just for vanity, as I demonstrated. Your first statement is correct, your conclusion isn't.

Lots of apps use 2GB, I'm guessing your experience is limited. Open a massive photoshop file, encode some videos, run a database. Games will generally not exceed 1GB. Most people will not use that much RAM in their entire system much less a single app, but it happens.

 
Phoenix86 said:
More RAM will help with handeling the rest of the system's apps and the OS. Having more than 2GB is not just for vanity, as I demonstrated. Your first statement is correct, your conclusion isn't.

Lots of apps use 2GB, I'm guessing your experience is limited. Open a massive photoshop file, encode some videos, run a database. Games will generally not exceed 1GB. Most people will not use that much RAM in their entire system much less a single app, but it happens.

Click to expand...

I have experience with photoshop and encoding/editing videos (video work is my primary job).
Our video editing machines at the office have 512megs of ram and operate great since the editing card handles all of the video and effects functions, Matrox RTX.100 cards.
 
WS6 said:
that is what I said. IF you have a program that will use 2gigs, then more ram will help, but what app uses that much physical ram at any one time?
Click to expand...
Any adobe app will
 
WS6 said:
I have experience with photoshop and encoding/editing videos (video work is my primary job).
Our video editing machines at the office have 512megs of ram and operate great since the editing card handles all of the video and effects functions, Matrox RTX.100 cards.
Click to expand...
I'm not sure what your point is. All the applications I listed will use 2GB RAM, what you use is irrelevant to your conclusion that more than 2GB RAM is for vanity. Apps do indeed use 2GB, you can run multiple apps, even multiple instances of an app and use all 4GB, more if it was avaialble.

You can open a *single* photoshop/premier file and use 2GB, all depends on how big the file is.

You can also extend the 2 GB limit to 3GB by extending the physical address extension (/PAE switch on the kernel).

Read me.

 
The one problem with having over 2GB of memory, that a lot of applications check physical memory and bail saying they don't have enough. They used a Signed Int to check which maxes out at 2GB. :( I run into this fairly frequently, and it's a dumb simple coding mistake that caused it. :(

But my 3GB is used in my system. That I can assure ya. ;)
 
Ranma_Sao said:
The one problem with having over 2GB of memory, that a lot of applications check physical memory and bail saying they don't have enough. They used a Signed Int to check which maxes out at 2GB. :( I run into this fairly frequently, and it's a dumb simple coding mistake that caused it. :(

But my 3GB is used in my system. That I can assure ya. ;)
Click to expand...
Are you running /pae?

 
No. I could in theory use the /3GB switch, but that screws the kernel for address space, and I don't want to do that.

I don't run any programs that require PAE so I don't turn that on. (My homebox doesn't regularly run Exchange or SQL server.) ;)

Edit:
Bah, Fixing a typo. [MS] Got me. ;)
 
Ranma_Sao said:
I run into this fairly frequently, and it's a dumb simple coding mistake
...
.... (My homebox doesn't regularly run Exchange or SQL server. ;)
Click to expand...

Good thing missing parens are caught by the compiler ;).
 
Hey guys, I just built up a NEW AMD X2 system with 4GB of memory. Running Windows XP SP2. SYSTEM reports only 3.25GB of memory. Is this correct? Is it because the memory limitation spoken of in this thread?
 
Mug said:
Hey guys, I just built up a NEW AMD X2 system with 4GB of memory. Running Windows XP SP2. SYSTEM reports only 3.25GB of memory. Is this correct? Is it because the memory limitation spoken of in this thread?
Click to expand...

Sounds like a problem, i assume your using 4x1gb sticks, why don't you try using two at a time and see if both sets report 2gb. If one set is reporting 2gb, and another is reporting 1.25 the probably one of those sticks is faulty, maybe even a pair.

Post more Specs as well. Like mobo manufacturer/model, ram brand
 
RogueTrip said:
Sounds like a problem, i assume your using 4x1gb sticks, why don't you try using two at a time and see if both sets report 2gb. If one set is reporting 2gb, and another is reporting 1.25 the probably one of those sticks is faulty, maybe even a pair.

Post more Specs as well. Like mobo manufacturer/model, ram brand
Click to expand...
Nope, no problem with it, or shouldn't be.

PCI reservations and other miscellaneous stuff reserved outright by the system.
 
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