AutoCAD Memory usage sky high

[irneb]

Is the boot.ini configured for the 3GB switch?

Note that has some strange effects. If you don't have it turned on, then WinXP-32bit can only use a maximum of 2GB of RAM (no matter how many chips are inserted on your motherboard). If it's turned on you can theoretically use up to 4GB, but practically very seldom much more than 3GB. And there's some graphics card issues when the 3GB switch is turned on.

 

IMO if you're using any ACad later than 2008, go with 64bit - at least because you can then use more RAM without much other hassles. Actually, I'm surprised you're using ACad 2010 on XP32. We steered clear of upgrades for several years because of the absolutely stupid slowness of newer ACads on old PC's. We're on subscription since 2005, but held back on the 2008 ACad and 2009 Revit versions - only upgrading this year to 2012 for both because only now did we have hardware capable of running those at least as fast as 2008 ran previously.

 

That's the one thing our IT guys keep forgetting: "But subscriptions are cheaper and you've always got the latest version" ... A: "Yes, but the hardware can't handle the new versions. Even if it can, it WILL be a lot slower than the old version."

[ReMark]

Yes, some graphics cards do not respond well to a change in the boot.ini file that enables the 3GB switch. I've had that happen on one out of three machines I've used this trick on.

 

Yes, Windows will never recognize the full 4GB of installed RAM. I think the best I could do on one of my old XP computers was to get Windows to acknowledge 3.2GB out of 4GB.

[irneb]

Yep, if you have 4GB of RAM installed on a 32bit machine - you've been screwed. There's no possibility of using more than 3.#~. The reason is the 4GB limit is a limit on the addresses any 32bit OS could possibly use for all of it's memory access. And seeing as most additions to a PC uses DMA (Direct Memory Access) - these take up addresses from the available pool. E.g. say your HDD/CD/DVD takes up a few megs of address space, the IO controllers for keyboard/mouse, etc. But the most hungry one is the Graphics Card - if it contains RAM of its own, that is also deducted from the main pool of addresses. If it's shared RAM, then it's also deducted from the physically installed RAM chips.

 

I've seen many fall for something like this: XP32, 4GB RAM, 2GB discreet Graphics Card . That means that even if you turn on the 3GB switch you'd be extremely lucky to get the full 2GB use - the graphics card is already using half the available 4GB address space - making it impossible for the OS to even address the last 2GB on your RAM chips, never mind any other peripherals. Thus at least half the 4GB chips are a wasted buy, that is until you can install a 64bit OS (which has a much larger address pool, theoretically 4GB^2, practically from 32GB to 500GB - depending on some other restrictions).

[SLW210]

Yep, if you have 4GB of RAM installed on a 32bit machine - you've been screwed. There's no possibility of using more than 3.#~. The reason is the 4GB limit is a limit on the addresses any 32bit OS could possibly use for all of it's memory access. And seeing as most additions to a PC uses DMA (Direct Memory Access) - these take up addresses from the available pool. E.g. say your HDD/CD/DVD takes up a few megs of address space, the IO controllers for keyboard/mouse, etc. But the most hungry one is the Graphics Card - if it contains RAM of its own, that is also deducted from the main pool of addresses. If it's shared RAM, then it's also deducted from the physically installed RAM chips.

 

I've seen many fall for something like this: XP32, 4GB RAM, 2GB discreet Graphics Card . That means that even if you turn on the 3GB switch you'd be extremely lucky to get the full 2GB use - the graphics card is already using half the available 4GB address space - making it impossible for the OS to even address the last 2GB on your RAM chips, never mind any other peripherals. Thus at least half the 4GB chips are a wasted buy, that is until you can install a 64bit OS (which has a much larger address pool, theoretically 4GB^2, practically from 32GB to 500GB - depending on some other restrictions).

 

I have previously posted information PROVING that the MYTHICAL 4GB limit on 32-bit is just a software licensing limitation imposed by Microsoft.

 

 

READ THIS

[ReMark]

Most average users won't attempt what is outlined in that article. It's hard enough just getting them to consider using the 3GB switch. Only a true diehard geek will attempt what the author suggests.

[irneb]

I have previously posted information PROVING that the MYTHICAL 4GB limit on 32-bit is just a software licensing limitation imposed by Microsoft.

 

 

READ THIS

There is something called PAE (Phisical Address Extension), some OS's (32 bit that is) allow any process to use this feature of a 32bit CPU (not all CPU's allow such though) to swap such "extra" RAM in and out of the process's space. But any one process can only have a maximum of 4GB at any one time. This is a lot like to old DOS limit which allowed swapping to >1MB through Extended RAM. Most MS operating systems don't allow this swapping, only the Server OS's from M$ do, nearly all Linuxes allow such though.

 

http://stackoverflow.com/questions/181050/can-you-allocate-a-very-large-single-chunk-of-memory-4gb-in-c-or-c/188564#188564

 

And even if you go through that hacking to turn on PAE, ACad isn't written to make use of it, so at best ACad would be limited to 4GB.

[lamensterms]

Are you aware that if you select items before you start the 3D ORBIT command that it acts differently?

 

As far as I had been aware, and I never really looked too far into it, the pre-selected ORBIT/3DORBIT command will perform a 'focused' orbit on the selected objects, hands for if the user only wants to inspect a few entities. Is this not true?

 

Since you mentioned there is 4GB of RAM installed and you are running WinXP I have to ask. Is the boot.ini configured for the 3GB switch? Have you done any tweaking of your virtual memory settings?

 

As far as I know - there have been no modifications to the boot.ini file. I haven't done any tweaking.

 

We steered clear of upgrades for several years because of the absolutely stupid slowness of newer ACads on old PC's.

 

We had held off on updates for a while as well. We had been using 2002 from 2004 to 2009, at that point we switched to 2009, and now 2010. So we've certainly fallen into the trap of software upgrades without worthy PC upgrades. We have replaced most of the machines over the years, but we never stepped up from 32-bit to 64-bit.

 

Thanks again for all the input guys. We are learning more about the problems with our systems, still gunna be hard to get action to be taken.

 

Cheers.