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Running Windows XP Pro w/ the 3 Gb switch enabled


Running Windows XP Pro w/ the 3 Gb switch enabled

A couple of months ago a thread was posted in which some users had difficulty in getting their systems to work with the 3 Gb switch enabled (this allows windows XP Professional workstations to use up to 3 Gb of memory, 1 Gb more than in the "standard" configuration).

This past week I configured my system to run w/ the 3 Gb switch, and ran into some problems as well. Here are the relevant Microsoft KB articles I referenced to get the system to work.

Microsoft KB 819636 - If your system has multiple SCSI controllers, this XP patch is req'd
Microsoft KB 829364 - Install this if your system fails to boot w/ a "Stop" error message
Microsoft KB 328269 - This one did the trick for me. If you have XP service pack 1 installed, you probably need this patch

Some other points that were not too apparent on the Microsoft site:

The /3GB needs to be the last argument in the OS option line. The only argument that can follow it is /USERVA

When you edit your boot.ini (see KB article 289022) add the /3GB option to a new OS option line (copy the existing line and give it a new name). If you fail to add this additional line, and the system does not boot, you'll need to boot from a CD..... An example of the boot.ini is shown below:

[boot loader]
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional 3 GB" /fastdetect /3GB

If you add this second OS boot option, if the 3 Gb boot fails, you can still select the non-3 Gb option for booting.

If you are running Wildfire, you still need to enable the 3 Gb option in the solver (msengine) per the PTC Knowledge base article. In Wildfire 2.0 this setting is on by default.

I hope this helps out, and the usual disclaimers about backing up the system, and that PTC does not support the changes to the OS.


John Buchowski
Product Line Manager
PTC Simulation Products
Main 408-764-8500
Direct 408-764-8710
Fax 408-764-8700
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