Amount of memory I can get.

[dragonfly22588]

Hey everyone,

I remember awhile back someone saying that windows xp only recognizes up to 3.5 GB of memory. What if I have XP Pro (32 bit) will it make a difference. I was thinking of upgrading to these: http://www.newegg.com/Product/Product.aspx?Item=N82E16820145184 Seem to be a steal.

 

[mikrev007]

No, xp pro 32 is also crippled.

 

[boonality]

So here's the thing right. 32 bit operating systems can only use 4GB of memory. This is all inclusive... in other words this includes your video memory and a few other small things that will make your computer "see" less than 4GB of RAM installed.

What are you running now? If that is an upgrade from say 2GB or something then it will still be fine.

 

[dragonfly22588]

This is the system I'm using:

Gigabyte 965P-DS3, PSU: 550 W Athena
Intel Core 2 Duo E6600 @ 2400 MHz
Corsair XMS2 DDR2-SDRAM PC2-6400 5-5-5-18@400 Mhz 2048 MB (2 x 1024 DDR2-SDRAM )
Nvidia Corp GeForce 7900 GTO 256 MB)EVGA

Does anyone know why it doesn't show up in my signature box even though I put it in there?

 

[photonboy]

Go ahead and buy the RAM. You will see a slight boost in general multi-tasking. Most games won't benefit.

I'm guessing 32-bit Windows will recognize about 3.3GB of it.

As mentioned, 32-bit systems are limited to 4GB of addressing which includes the RAM, video card etc. It's not a Windows limitation it's a hardware limitation. A single line is ON or OFF (2 address locations) and 32 lines with all those ON/OFF combinations maxes out at 4GB of addressable space. Okay?

I noticed an obviously snappier overall experience when multitasking when going from 2GB to 4GB in Vista x64.

You might wish to get a copy of Windows 7 RC 64bit when it comes out on May 5th. it'll be good for probably 6 months to a year. This may help you decide to get an OEM copy when it's released. It'll be fun to try and it's free. You may wish to dual-boot. Either way, do a fresh install. Acronis Disk Director 10 is a great Partition Manager for adding a second hard drive partition or changing existing sizes. There are programs but I know this one works great.

Also, I didn't notice what your hard drive was. Your money might be better spent on a newer hard drive. Adding more RAM, or improving hard drive speeds will both speed up your system, but in slightly different ways. You can go to the hard drive manufacturers to find out the specs.

FYI about video cards:
A 1GB video card in a 32-bit system might drop your maximum possible RAM to 2.5GB. In SLI (two cards) the RAM is "cloned" for anti-aliasing etc but the actual system only "sees" 1GB, not 2GB.

 

[mikrev007]

It's not a Windows limitation it's a hardware limitation.

But it is (a Windows limitation). A 32bit OS is not confined to 32 address lines.

 

[huron]

It's not a Windows issue - it's a 32-bit issue. If you get 32-bit OS of any type, it will only be able to see/use 4GB of RAM (max). Windows sees a little less because of the way that it reserves address space for some hardware/devices.

It is because it is 2 to the 32nd power (just over 4GB of RAM).

 

[mikrev007]

But again, the number 32 is not the highest number of possible address bits in a 32bit OS.

 

[photonboy]

Uh, no. huron and I have it basically covered.

I'm not going into the slightly more complicated involving extendable addressing etc. Basically it's a 2exp32 issue involving Windows allocating a small amount and the RAM, video, BIOS etc taking the rest.

But you go ahead and get 6GB of RAM working under XP 32-bit. I'll be impressed.

 

[mikrev007]

As said, 32bit XP is crippled in such a way that it cannot use more than 4GB by itself (you can install software that will). There was a statement that the hardware was the limitation - which is not true (sure, it can be, but that would limit a 64bit OS as well).

 

[photonboy]

mikrev007 wrote
"a statement that the hardware was the limitation - which is not true (sure, it can be, but that would limit a 64bit OS as well). "

Yeah, 64-bit does a hardware limitation. Since available addressing doubles with every line added, 33-bit means 8GB and 34-bit is 16GB. No desktop computer is going to need 2exp64 of RAM.

Actually Microsoft just thought up some artificial maximum numbers for supporting RAM on various systems. I forget what they are.

32-bit XP is Not, I repeat, is not "crippled"; there's 4GB of total available addressing available and that's it. Windows will set aside a small portion for something we need not get into but the rest is for your video card, BIOS, other hardware and any System RAM up the 4GB total addressing limit if enough RAM is installed.

People seem to feel Windows is crippled by not using 4GB of RAM because they keep confusing the "Memory Map" (addressing space) to the physical System RAM.

 

[mikrev007]

It is a known fact that XP/SP2 even runs in PAE mode by default. So you have all the addressing bits you need. XP just doesn't make use of it.

If XP only wanted to use 2GB would you call that for crippled? I bet you would.

Windows doesn't set aside anything. This is a hardware (architecture) thing.

No matter how many bits you have in your OS, if the hardware limits you, you are limited. Some 64bit capable hardware cannot go beyond 4GB total memory. That was my point here.

PAE in a 32bit OS is a bit like running 32bit applications in a 64bit OS. Each application is limited, but in total you have access to much more than 4GB.

No desktop computer is going to need 2exp64 of RAM.

I replied to such a comment a few days ago. A x-bit OS doesn't have to mean 2^x bit physical address space.

 

[blackwidow_rsa]

PAE does not work at all, you need PAE supporting drivers and even when you do, it can be a buggy experience. That's why they disabled it in Vista. If i remember correctly PAE extends the address limit to 36bits. 64bit Windows OS's can only see up to 64TB of RAM, you can call that 'crippled' but XP is not, its just how addressing ALL the memory works (bios, cpu cache, ram, gpu ram, etc.)

 

[mikrev007]

You need drivers that have been written without taking shortcuts (there are some rules set out by Microsoft). They don't need to be "PAE" aware. A small portion of the drivers out there are bugged, according to Microsoft.

The number of bits available in PAE mode depends on the implementation. It can be more than 36.

If an OS doesn't make full use of the hardware, no matter the reason, I (and many others) call that crippled. Just as I said before: If XP was limited to 2GB, you would call that crippled, since it doesn't make full use of the hardware.

 

[photonboy]

mikrev007,
http://duartes.org/gustavo/blog/post/motherboard-chipsets-memory-map

Your video card (mainly your video RAM) would be in the "approx 1GB for PCI space" section. Windows and other software uses the large grey, roughly 3GB area.

I'm done trying to explain it. And I'm not going into PAE etc. Believe me or don't. Bye.

 

[mikrev007]

I am not talking about the MMIO space allocated from 4G and down. I am talking about addressing more than 4GB. XP is crippled in such a way that it will not do that. Okay?

The addressing bits are there. The memory manager just wont touch them. Hence, it is crippled. You cannot say otherwise.

If we take a look at this chart here:
http://msdn.microsoft.com/en-us/library/aa366778.aspx

It shows various memory limitations. The biggest 32bit edition goes up to 128GB. The smallest is limited at 1GB.

We can then discuss the reasons as to why XP is limited to 4GB, but it IS artificially limited.

 

[mikrev007]

To add a bit: DEP was introduced in XP/SP2, but even before that there was a PAE kernel. Before SP2 there was support for 4GB system RAM. If 5GB address space was needed to address those 4GB, it was provided trhough PAE. They removed that in SP2.

 

[photonboy]

mikrev007,
hmm.

there actually seems to be some proof to what you say. a lot of confusion out there even by so-called professionals

It probably was best to "cap" things though and wait for true 64-bit support.

anyway, you "win"

http://www.brianmadden.com/blogs/brianmadden/archive/2004/02/19/the-4gb-windows-memory-limit-what-does-it-really-mean.aspx