Thanks Scott.The 3GB switch option has been available for some time (Whats new 2004), + I'm a greedy person, and I want more than 3GB. Knowing that theres hardware out there which will support up to 8Gb of RAM, I'm determained to work out if I can get to use all of it, and XPx64 gives me that opportunity. Initially I intend to be purchasing 2GB, but will be getting another 2GB the month after. The info I have on the 3Gb switch is below, a friend at work sent it to me, if anyone else finds it useful??
The Perils of Trying to Overcome the 2GB Memory Limit
By Ed Eaton
If you crash SolidWorks or PhotoWorks because of insufficient memory, purchasing more RAM for your computer is only part of the solution.
No matter how much memory you have, or how big your virtual memory, Windows will not allow you to use more than 2GB for a single application.
On top of that, the 2GB is theoretical. In practice, applications crash when memory usage reaches about 1.6-1.7 GB. This of course will stop you cold if you are working on large assemblies, or on PhotoWorks renderings.
Because of the 32-bit operating system, the mathematical limit for total memory+virtual memory is 4GB. By default, Windows reserves half of that total for itself!
On page 7-12 of the SW2004 "what's new manual," there is a mention that SolidWorks is written to take advantage of the /3GB switch. This switch allows Windows XP Pro and some server applications to override the 2GB limit and free up to 3GB of that expensive RAM you've been buying for your systems.
Unfortunately, when our company attempted to follow the instructions as presented, we permanently prevented our system from rebooting.
After a great deal of extra research, we found that enabling the 3GB switch requires that you know a poorly documented two-step process.
The first poorly documented problem is that the /3GB switch is not working in Windows XP Pro, Service pack 1 (that's why the system locked up)! To get a hotfix that corrects the issue, you have to call (800) 936-4900 and get to the "hotfix" people. Don't get spooked by Microsoft's statement that they will charge $245 for tech support - hotfixes are free.
Let the person on the phone know the problem has to do with the /3GB switch, referred to in article 328269. The link for that article is support.microsoft.com/default.aspx?scid=kb;en-us;328269&Product=winxp
Microsoft will email you a hotfix that carries no warranty and is not recommended for use in a production setting unless you thoroughly test it. But, for the record, it worked for us, and I have not experienced any problems in the three months I've had it on my machine.
After running the hotfix, enabling the /3GB switch is not as simple as checking a box in a dialogue. You have to dig into your boot.ini file and modify it.
The boot.ini file is on the top level of your C: drive, but to make it visible you have to go through Windows Explorer Options, Tools, Folder Options, View and select "Show hidden files and folders" and deselect "Hide protected operating system files."
The modification to the boot.ini file is explained in the following article:
The text of your boot.ini file may not match the sample shown. For reference, here is what I had to do to mine:
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /3GB /fastdetect
A final warning: Yes, enabling the /3GB switch has worked for us, and allows us to use up to 2.7GB of RAM before locking up SolidWorks or PhotoWorks. We are now able to perform tasks that were simply not possible before the modification. But as with any time we hack our systems for performance, there are risks. Before starting on this process, I made a complete backup of my boot drive than I could plug in and use if things went south.