Vista Mythbusters #2: Dual-core and 64-bit support

Will Windows Vista support dual-core CPUs? How will 64-bit Vista versions be delivered? Get the answers in the latest installment of my Vista Mythbusters series.

This is the second in my series on Vista myths. A pair of questions keep popping up in the Talkback section whenever I write about Windows Vista, so let's deal with them right now.

Myth: Some versions of Windows Vista won't support dual-core CPUs or 64-bit processors.

Reality: Every Vista version supports dual-core processors, and every version is available in a 64-bit native version as well.

Part of the confusion rests with the specifications for some fairly exotic hardware. If you have a PC with multiple physical CPUs - that is, two or more chips installed on the motherboard - you'll need Windows Vista Business, Enterprise, or Ultimate to take advantage of both CPUs. If you install Vista Home Basic or Home Premium, the OS will only recognize one CPU. That's similar to the way Windows XP works today - if have a dual-CPU machine, you need to install XP Professional to use both CPUs.

So what about dual-core CPUs? That's different. All Vista versions, even the lowly Home Basic, support multiple cores on a single chip, with no additional configuration required.

Update 13-November: Don't just take my word for it. Before dual-core chips reached the market, Microsoft publicly declared that its definition of processor encompasses physical CPUs, not individual cores:

On October 19, 2004, Microsoft announced that its server software that is currently licensed on a per-processor model will continue to be licensed on a per-processor, and not on a per-core, model. This policy will allow customers to recognize more performance and power from Microsoft software on a multicore processor system without incurring additional software licensing fees.


The story with 64-bit Windows is a little more complicated. Today, Windows XP Professional is available in separate 32-bit and 64-bit versions that are functionally identical but must be purchased separately. In Vista, every version will be available in both 32- and 64-bit versions. A Microsoft spokesperson tells me they're still working out the details, but the current plan is to include 32-bit versions in retail packages; if you want to install a 64-bit version, you'll have to call and request that the alternative media be sent to you. The same spokesperson says Microsoft may include both 32-bit and 64-bit DVD media in the Windows Vista Ultimate box. For $399, that sounds like the right thing to do.

Previously in this series:

Vista Mythbusters #1: It's not a hardware hog