Windows XP x64: start of a new era?

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Rob Jamieson revisits an area which is very important for the design sector, but not necessarily as important to general computing. 64-bit Windows is shipping but does it work for mainstream CAD?

The memory usage of a model changes when you do operations to it. Here we have a model views laid out in Inventor, but as soon as you edit the views the memory usage shoots up to 3.46GB. Once the edit is complete is settles back down to 2.8GB. It is more than just loading a 3D Model that uses the RAM you always need a bit extra or you will use the swap on the hard disk and slooowww down or crash!

If you are a Unix user there have been many ways to get access to more RAM than is made available in Windows due to its imposed limit, but for most users who today rely on Microsoft’s OS it has not been so easy. So what is the limit? I often get asked by CAD users, ‘why do they need Windows XP x64 when their 32-bit Windows XP system has 3GB or 4GB of RAM?’

Under Windows XP a single process can only allocate 2GB of RAM to this one process, this being your CAD application. The CAD or Design Program can only address this amount of RAM regardless of the physical amount in your machine as it’s an OS imposed software addressing limit. You can cheat and use the /3GB switch in the boot.ini file, but only certain applications can understand this and see 3GB. However, other applications can become “flaky” as this moves the allocated resources for graphics etc into other areas which these other applications might not understand. There are one or two exceptions to the rule with Microsoft email packages but that’s out of our area of design.

Working with XP x64

I installed Windows XP x64 on several systems and added some 32-bit CAD software to see how it works. I’m not going to talk about relative performance issues as this is the reserve of MCAD labs. Instead, I’m going to look at it from a user point of view to see how viable it is to use this in a working environment today. Unfortunately today there is little CAD software that has been recompiled into 64-bit code and some of the solid modelling kernels are going to take a long time. There is (or will be soon) some 32-bit CAD software, which is 64-bit aware from the point of view from memory addressing, so this is what we are really looking at today. This gives you the ability to load larger files with a 32-bit program imposed limit of 4GB. This is double what you have today with Windows XP!

The first machine I had was a dual Fujitsu-Siemens Opteron with 6GB of RAM. Windows XP x64 Edition installed OK so I added ATI’s FireGL 64-bit graphics driver and some CAD software. Once you have XP x64 up and working don’t expect a massive leap from XP, it looks just the same. You will have to wait for Windows Vista – previously referred to by its internal code name Longhorn – with its new 3D interface, before you will see any changes. Now I don’t favour any CAD vendor but I do have access to some software quicker than others so I put on Inventor 10 and 3dsmax 7.5. Inventor installed after I manually downloaded Netframework but the installer for 3dsmax crashed every time. If you went into the folders and manually installed each module 3dsmax did install OK.

Well there’s no point in having all this memory and not putting it to good use so I created a new assembly and added in two large Mastenbroek trench diggers. This took the memory straight up to 2.25GB. It’s no good patterning the model as this does not add weight i.e. use any more RAM. After adding more models I got to 3.4GB but I think this was putting a strain on the software and it was slowing down the file allocation with hard disk etc. It did not crash though!

I ran 3dsmax at the same time and the first thing it did was run on the same processor as Inventor. I could pattern large files but it became a little unstable. I wasn’t very fair on max as I was running another intensive application at the same time.


After I had created a large dataset I copied it off onto a portable USB drive (it was very slow) and sent the Opteron system back where I had borrowed it from. Now it was time to have a look at a workstation in the interesting price point of ú1,500, a P4 EM64T with PCI Express and 4GB of RAM from RMT. I added an extra drive so I could keep the Raid 0 with XP intact. Now this new drive had a beta of x64 so I bravely did an upgrade (I never normally recommend you do this as you end up with all the guff you had last time) and it worked fine! There were a lot more unknown devices in “device manager” so a quick trip to the manufacturers’ web site and I was able to pull down and install these. The interesting thing is they were all labelled “beta drivers” but they all worked fine. Manufacturers do this when they are not sure if everything is going to work OK; it gives them a free “get out of jail” card. On went the ATI FireGL graphics 8.1.33 driver followed by Inventor and 3dsmax as before. I started to copy the CAD files off the USB drive but they were all corrupt, other files on the drive were fine so it was the USB drivers on the Opteron that were faulty. I checked the site and no updates for that system were available. Three hours down the line after I had rebuilt and re-migrated the files I tested loading up two trench diggers. The performance was similar to the Opteron but 3dsmax was more reliable.

Inventor reported in its “about” file that it could see 4GB of RAM. This is very important as when you create drawing views you need extra memory to find all the files before all the hidden line algorithms can work out what should be in the front and behind etc.

This system was the older 3.6GHz Pentium 4 EM64T motherboard (925 chipset) so it lost some allocated memory but acquitted itself fine. The newer 955 chipset RMT workstation would not lose this memory. As I type away now in Word 2003 on the x64 workstation I’m tempted to see what else works OK.

After a frustrating hour I could not get AutoCAD 2006 to install – there were problems with Demoshield 7.5 (similar to 3dsmax installer problems but you could get around it). Utility software such as Nero and DVD players were fine. Only the latest virus checkers would install, earlier ones complained.

The main conclusion that can be drawn from this exercise is that x64 is very new. You need “branded” hardware with good driver support, patience and a good understanding of how to install device drivers. Your CAD vendor will need to say that their application is supported. Inventor 10 still has a slight problem with content centre under x64 so it’s still not officially supported. If you are reaching your limit in model size or it takes ages to produce drawing views because you are out of RAM and it’s mission critical to get a solution, Windows XP x64 Edition is here now, just be careful!

Robert Jamieson works for workstation graphics specialist, ATI.


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