I am surprised to discover that 64-bit Windows Vista is not supported on the latest iMacs. The hardware to support it is all there and it even runs on the Mac Pros and MacBook Pros so I would have thought the same would apply to the iMac, but alas this is not the case. There is one very big reason to use the 64-bit version over 32-bit: memory. The 32-bit version of Windows Vista supports a maximum of 4GB of RAM but it will not fully utilize it. Mark Russinovich from Sysinternals explains the reason for this on his blog. Basically, with a 512MB Video card that would leave me with 3.5GB of usable RAM at most.
After quite a bit of research and trial and error I was finally able to get 64-bit Windows Vista Ultimate running on my iMac. So, without further ado, here’s how.
Getting the drivers
You can go ahead and partition your hard drive with the Boot Camp Assistant and perform the installation normally. The trouble comes after you have booted into Windows and are trying to install the drivers. The iMac installation DVD does not come with 64-bit drivers so you will need to obtain them from a Mac Pro disc. Fortunately, someone has already uploaded these to rapidshare: Part 1, part 2, part 3, and part 4. You will also need to download the Network Controller drivers for Windows Vista x64 (64-bit) from Marvell. Extract the Boot Camp Drivers and burn the contents along with the Network drivers to a CD/DVD (flash drive will work too).
Installing the drivers
First, install the Boot Camp Software by running BootCamp64, located in the Drivers > Apple folder. News, install the network adapter driver you downloaded from Marvell. Finally, wire up so that you can access the internet and run the Apple software update program to get the Boot Camp 2.1 drivers.
If your iMac was similar to mine all that’s left is the wireless network adapter. Surprisingly, Windows can find and install that one for you—just wire up, head to device manager, and Update Driver Software. Once everything is taken care of you can run the Windows Experience test to activate the aero glass theme.
Other notes (and problems)
Cutting edge video drivers—while I found the drivers on the Mac Pro disc satisfactory (index score of 5.8), you may like to try the latest drivers to see if you can milk anything more out of your card. The generic nvidia drivers will not install without tweaking the INF file, so LaptopVideo2Go is your best bet.
Audio playback glitches—you may notice that during audio playback the sound pops or crackles. It appears that the Broadcom 802.11 wireless card is to blame. If you disable that device your sound problems should go away. I tried every compatible driver I could get my hands on to solve the problem, even those from Dell and HP. Some reduced the effect but the pops were still annoyingly noticeable. Fortunately the Marvell controller does not have the same negative side effect.
Elgato EyeTV—drivers for the Hauppage WinTV-HVR worked to enable digital reception with my Elgato EyeTV for use in Media Center. I don’t remember the exact one I downloaded but I’m pretty confident it was the 950 (not 950Q).
Hopefully I’ve been able to provide enough information for you to get Windows running on your own iMac. Now it’s time to try out some of those games that you can only get on the Windows Platform. Microsoft Flight Simulator X is one of my favorites.
Please share any additional information or solutions for some of the problems if your run across something.