Intel Macs are Still Limiting RAM Usage to 2 GB under Windows XP

I'm running Windows XP on my Mac Pro, but a really annoying limitation is that XP can only see 2 GB of my 5 GB of installed RAM. When I researched this a couple of months ago, I found out that this is a firmware/software limitation that can only be fixed by Apple and Intel. Until they make sure that Windows XP can see all installed RAM, using a Mac Pro for Windows production is severely limited.

There's a widely spread misunderstanding that this problem can be fixed by using the /3GB switch in Windows' boot.ini file, but this technique can only be used to make certain applications use a bit more memory, as I showed in Using more than 2GB of RAM in After Effects, but it doesn't solve this problem at all.

So what are the options? One is using Windows XP x64 or even Vista64 (for the adventurous) that will let you see and use all your installed RAM. You don't even need Apple's Bootcamp at all (not even for the regular XP.) Instead, add an extra hard drive and install Windows on the new drive (insert the installation DVD/CD, restart and hold down the C key to boot from it.) You can download the nVidia/ATI graphics drivers from the web, as well as the audio drivers from Realtek. The Apple keyboard works without drivers, and you just hold down the Alt / Option key when booting to choose which OS to boot from.

Since you can't directly buy or upgrade to XP x64, I haven't tested this. I just hope that this info becomes more widespread, so that Apple/Intel fix this big limitation.

- Jonas

Photo by @Paul