What’s the Difference Between 32-bit and 64-bit Windows?


Whether shopping for a new computer or upgrading an old one, you’ve likely come across the the “64-bit” designation and wondered what it meant. Read on as we explain what Windows 7 64-bit is and why you’d want a piece of that 64-bit pie.

Windows 7 and 8 have done an enormous amount to increase the popularity of 64-bit computing among home users but many people are unclear on what exactly it means (and may not even realize they’re already running it). Today we’re taking a look at the history of 32-bit and 64-bit computing, whether or not your computer can handle it, and the benefits and shortcomings of using a 64-bit Windows environment.

A Very Brief History of 64-bit Computing


Before we start dazzling you with interesting history, let’s get the basics down. What does 64-bit even mean? In the context of discussions about 32-bit and 64-bit personal computers the XX-bit format refers to the width of the CPU’s register.

The register is a small amount of storage used by the CPU where the CPU keeps the data it needs to access the quickest in order for optimum computer performance. The bit designation refers to the width of the register, thus a 64-bit register can hold more data than a 32-bit register which in turn holds more than 16-bit and 8-bit registers. The more ample the space in the CPU’s register system the more it can handle, especially in terms of utilizing system memory. A CPU with a 32-bit register, for example, has a ceiling of 232 addresses within the register and is thus limited to accessing 4GB of RAM. This may have seemed like an enormous volume of RAM when they were hashing out register sizes 40 years ago but it’s a rather inconvenient limit for modern computers.

Although it may seem like 64-bit computing is the new kid on the techno-wizardry block, it has actually been around for decades. The first computer to utilize a 64-bit architecture was the Cray UNICOS, which sets a precedent for 64-bit super computers (the Cray 1 is seen in the center of the photo above). 64-bit computing would remain the sole province of super computers and large servers for the next 15 or so years. During that time consumers were exposed to 64-bit systems, but most were completely unaware of it. The Nintendo 64 and the Playstation 2, both seen in the photo above, had 64-bit processors a full 5 years before consumer level 64-bit CPUs and accompanying operating systems even make a faint appearance on the public radar.

Consumer confusion over what 64-bit means to them and poor driver support severely hampered the push towards 64-bit personal computers throughout most of the 2000s. In 2001 Microsoft released Windows XP 64-bit edition which, save for those wanting to deal with extremely limited driver support and many headaches, was not widely adopted. The following year OS X Panther and a handful of Linux distributions began supporting 64-bit CPUs in varying capacities. Mac OS X didn’t fully support 64-bit for another five years with the release of OS X Leopard. Windows supported 64-bit in Windows Vista but, again, it wasn’t widely adopted. All around it’s a bumpy road for 64-bit adoption among home users. The release of Windows 7, however, turned things in favor of 64-bit computing and many off-the-shelf computers now ship with Windows 7 64-bit.

Can Your Computer Handle 64-bits?


Whether you’re a Windows XP holdout contemplating an upgrade to Windows 7 or you’re curious if your computer running Windows 7 32-bit can handle an upgrade to Windows 7 64-bit, there are a few handy ways to check.

You can check your version of Windows installation to see if you’re already running a 64 bit OS. Under Windows Vista and Windows 7 all you need to do is right click on Computer in the Start Menu and click Properties in the right-click context menu. This will take you to the System Properties menu (as seen in the screenshot above) and show you, under System type, whether you have a 32-bit or 64-bit operating system.

If you’re running Windows XP you can check in a similar fashion but the chances of you being a Windows XP 64-bit user are fairly slim. The most important step you can take with an XP machine (or a Windows Vista/7 machine running the 32-bit version) is to test your processor and see if it’s even possible for you to upgrade to a 64-bit version of Windows.


To perform the test you’ll want to grab a copy of Steve Gibson’s free and portable application SecurAble. Seen in the screenshot above, SecurAble tests for three processor variables. First it tests your processor to see if it is 64-bit. Second, it checks to see if the chip supports D.E.P. (a security technology designed to protect machines from “unchecked buffer” attacks). Finally, it indicates if your machine can handle Windows XP virtualization under Windows 7 (hardware virtualization has other applications, but the much talked about XP virtualization under Windows 7 is by far the best known use). If you’re curious you can click on any of the results in SecurAble to get a more detailed run down of the results and what they mean. In the case of our test machine, seen above, the CPU is good to go for 64-bit computing, D.E.P. protection, and hardware virtualization.

The Benefits and Shortcomings of 64-bit Computing


You’ve read a little on the history of 64-bit computing and your system check indicates you can run Windows 7 64-bit. Now what? Let’s run through the pros and cons of switching over to a 64-bit operating system.

What do you have to look forward to if you make the leap? Here are some of the enormous benefits to making the jump to a 64-bit system:

  • You can rock radically more RAM. How much more? 32-bit versions of Windows (and other OSes for that matter) are limited to 4096MB  (or 4GB) of RAM. 64-bit versions are theoretically capable of supporting a little over 17 billion GBs of RAM thanks to that spacious register system we talked about earlier. Realistically, Windows 7 64-bit Home editions are limited (because of licensing issues, not physical limitations) to 16GB of RAM and the Professional and Ultimate editions can rock up to 192GB of RAM.
  • You’ll see increased efficiency. Not only can you install more RAM in your system (easily as much as your motherboard can support) you’ll also see more efficient use of that RAM. Because of the nature of the 64-bit address system in the register and how Windows 64-bit allocates memory you’ll see less of your system memory chewed up by secondary systems (like your video card). Although you may only double the physical amount of RAM in your machine it will feel like way more than that because of the new efficiency of your system.
  • Your computer will be able to allocated more virtual memory per process. Under 32-bit architecture Windows is limited to assigning 2GB of memory to an application. Modern games, video and photo editing applications, and hungry applications like virtual machines, crave large chunks of memory. Under 64-bit systems they can have, brace yourself for another big theoretical number, up to 8TB of virtual memory. That’s more than enough for even the craziest of Photoshop editing and Crysis sessions. On top of the more efficient use and allocation of memory, applications optimized for 64-bit operating systems, such as Photoshop and Virtualbox, are super fast and take full advantage of the spaciousness of the processor and memory afforded to them.
  • You’ll enjoy advanced security features. Windows 64-bit with a modern 64-bit processor enjoys additional protections not available to 32-bit users. These protections include the aforementioned hardware D.E.P., as well as Kernel Patch Protection that protects you against kernel exploits, and device drivers must be digitally signed which cuts down on the incident of driver-related infections.

That all sounds wonderful, no? What about the shortcomings? Fortunately the list of shortcomings that come with adopting a 64-bit operating system is increasingly smaller as time goes on. Still there are a few considerations:

  • You can’t find 64-bit drivers for older but critical devices on your system. This one is a serious deal killer. Fortunately vendors are increasingly supporting 64-bit operating systems (you should have little problems with hardware manufactured in the last year or two). Unfortunately you’ll be hard pressed to get drivers for older devices. Have an expensive sheet-fed scanner from 2003? Love it? Too bad. You’re probably not going to find any 64-bit drivers for it. Hardware companies would rather spend their energy supporting new products (and encouraging you to buy them) than supporting older hardware. For small things that are easily replaced or need to be upgrades anyway, this isn’t a big deal. For mission critical and expensive hardware it is. You’ll have to decide for yourself if the upgrade cost and tradeoffs are worth it.
  • Your motherboard doesn’t support more than 4GB of RAM. Although it’s rare it’s not unheard of to have a motherboard that will support an early 64-bit processor but not support more than 4GB of RAM. In this case you’ll still get some of the benefits of a 64-bit processor but you won’t get the benefit that most people crave: access to more memory. If you’re not buying bleeding edge parts, however, hardware has gotten so cheap lately that it might be time to retire the old motherboard and upgrade at the same time you’re upgrading your OS.
  • You have legacy software or other software issues to deal with. Some software doesn’t make the transition to 64-bit smoothly. Unlike previous versions of Windows, Windows 7 64-bit has no support at all for 16-bit applications. If by some chance you’re still using a really old legacy application for something you’ll need to either virtualize it or forgo an upgrade. Also, just because an application is 64-bit doesn’t mean the plugins and extensions for it are. Photoshop and Firefox are common applications where people run into this problem. The core application is available in an updated 64-bit form but important plugins are not.

Before we leave the cons side of things, I’m going to weigh in on a personal level. I have been running Windows 7 64-bit for nearly 2 years now and I have run into only a single issue related to the operating system being 64-bit. Everything has functioned smoothly, I’ve enjoyed rocking 8GB of ram, I’ve run half a dozen virtual machines at one time without a hitch, and overall I’ve been extremely pleased. The only issue I ran into was trying to get my early 2000-era Canon scanner to function. Canon simply failed to produce a driver set for it and all the hacks and tweaks failed to coerce it to work. Ultimately I just bought a new and equally as cheap scanner for $50 and called it a day. All things considered it was a very nominal trade off and given how little I actually use a scanner it’s possible I might still be unaware it wasn’t working. 64-bit computing has become affordable, easy to use, and virtually headache free.

Have your own experiences with 64-bit Windows to share? Whether you were an early 64-bit adopter or are on the upgrade fence, let’s hear about it in the comments.


Jason Fitzpatrick is a warranty-voiding DIYer who spends his days cracking opening cases and wrestling with code so you don't have to. If it can be modded, optimized, repurposed, or torn apart for fun he's interested (and probably already at the workbench taking it apart). You can follow him on if you'd like.

  • Published 03/22/11
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