RAM limit in Windows XP Pro?

[Colin Braley]

This question gets asked alot, I suggest you search the archives for the terms RAM or search for all posts by a guy named Steve Forde. Also, try searching for the term 3GB Switch and RAM Black hole .
Anyway heres a run through of how much RAM you can and can’t use.
Well, all apps that you would run on XP Pro are 32 bit, and usually can adress only 2 GB of RAM. Some apps are “large address aware” and when you add the 3GB switch to the boot.ini file, can use up to 3 GB. For more than 3 GB of RAM you will need 64 bit windows.

[Jerome Thelia]

Thanks, I found Steve Forde’s post and am pasting it below.

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I have seen a recurring theme on the COW about confusion in terms of AE’s use of RAM. I will attempt to explain a couple of issues regarding how much RAM, 32 bit vs. 64 bit, ECC vs. Non-ECC, DDR vs. DDR2, and OS constraints. (will also try and make this as plain language as possible, leaving out as much geek speak as possible)

Question 1. How Much RAM can AE use?

Short Answer: ALOT! AE is what I would call a RAM beast. But there are limitations….

Detailed Answer: Win XP – 32 bit:

AE is a 32 bit application. A 32 bit application can only address a maximum of 4GB of RAM. Hard Stop. No 32 bit application can address more than this.

That said, Win XP 32 bit (Pro or Home) doesn’t allow 32 bit applications to access 4GB of RAM. The reason for this is, Win XP itself is a 32 bit application. It reserves a quantity of RAM just for itself, and one of the ways it does this is to limit ALL processes to fight over the same maximum amount of 2GB of RAM. What this means is, if you have five 32 bit applications open at the same time, they will all fight over the same 2GB’s of RAM irrespective of how much RAM you have.

This is also why Win XP 32bit will also not see any more than 4GB of RAM, no matter how much RAM is “really” there. In fact, adding more than 4GB of RAM on Win XP 32bit can cause the OS to get a little lost in the extra RAM space, and become unstable.

Therefore – Do not add more than 4GB of Physical RAM if you are running Win Xp 32bit (Pro or Home)! Just becuase you have the RAM slots, does not mean that Win 32bit will play nice with it!

AE will attempt to use all 2GB available to it if possible. This is why AE allows you to set RAM usage in the preferences. If you leave the default preferences the way they are, it will max your system. I would recommend not running ANYTHING other than AE when using the defaults. Lower the Max RAM and Image Cache sizes if you want to use other apps at the same time as AE.

One last note – some users will notice that not all physical RAM installed on a workstation is “seen” by windows. Right click on “My Computer” and show properties. It is common to see say only 2.75GB even though 4GB is installed. This is called “The Black Hole”. The reason for this is, PCI-Express. The BIOS of your workstation will take physical RAM away from windows to use as a buffer zone for the data transfer to PCI-Express devices, regardless of whether you have PCI-Express devices or not. The amount the “black hole” takes is relevant to the amount of RAM installed – the more RAM, the bigger the black hole.

Therefore, if you have PCI-Express on your workstation motherboard, you are very likely going to see the “Black Hole”.

[Oscar G.]

Hy!

Two switch to install in the boot.ini file : /3GB and /PAE (physical address extension).

all xppro that i use can’t see more than 3gb memory (i think this is a limitation from MS)

If you want more…in 32bit system use a windows 2003 server which is design o use 24GB max (if i’m not wrong) with PAE. But applications need to be specialy developed with PAE code. And you will need drivers wich works on 2003 server (like decklink wich has now xppro, 2003 and 64 bits drivers)

personnaly i didn’t try ppro2 an ae7 on a win 2003…

regards

oscar

Well, well, well…