Why it matters whether your Windows is 32-bit or 64-bit

There's a difference, and it involves your PC, too.

new windows 10 logo primary
Credit: Rob Schultz

Ken wrote in saying he loves PCWorld, natch, and that he wants to know the difference between 32-bit and 64-bit operating systems.

I have to admit this isn’t something I’ve thought about in a long time, but I peeked around and lo and behold Microsoft’s latest OS—Windows 10—is being offered in a 32-bit version. Microsoft says it has at least 71 million 32-bit users still (as of 2014), and didn’t want to leave them out in the cold, or thrust them into the open arms of Cupertino (headquarters of rival Apple). Given this situation, I figured I’d explain the main difference between the two.

First of all, if you’re wondering which version of the OS you have, you can easily check by right-clicking the Start button in Windows 10 and selecting System. It says right there in plain English which OS you are using. In Windows 7 and 8 (and 10) just click System in the Control Panel.

64bit

Windows tells you whether you have a 32-bit or 64-bit operating system. 

In addition to noting the type of OS you're using, it also displays whether you're using a 64-bit processor, which is required to run 64-bit Windows. Unless you have a really old PC (it would have to be over 10 years old), you should also have a 64-bit processor.

Now that you know what you have, does it matter? It could matter a lot, depending on how you use your PC. The biggest difference between 32-bit and 64-bit OSes is that the 32-bit version can only address a bit less than 4GB of memory, in total, for the entire system, and this includes the memory in your video card. For Windows it’s usually about 3.5GB total. For example, if you have a system with 4GB of RAM but your video card has 1GB of memory in it, that leaves just 2.5GB of memory for the OS to use, which isn't much at all for Windows.

Even worse, you could theoretically have an 8GB system running 32-bit Windows, which means there's 4GB of memory in your system that might as well be used as a drink coaster. Only 64-bit systems can address more than 4GB of RAM, so this one reason alone is why most people choose one over the other.

As my esteemed predecessor Lincoln Spector discussed previously, there is a workaround called Physical Address Extension (PAE) that allows 32-bit systems to address up to 64GB of RAM, but only server editions of Windows offer it.

Though there are other differences, the ability to address certain amounts of RAM is the main concern for most users. In fact, if you visit Microsoft’s FAQ on this subject, all it says is, “The 64-bit version of Windows handles large amounts of random access memory (RAM) more effectively than a 32-bit system.”

 Though this column isn’t about whether you should switch from 32-bit to 64-bit, if you’re considering it the one thing you want to check first is whether there are 64-bit drivers for your hardware, which should be the case unless your PC is ancient.

Finally, as far as Windows 10 is concerned, if you're running a 32-bit operating system (Windows 7 or 8) and perform an upgrade, Microsoft will give you the 32-bit version of Windows 10. If you want to move from 32-bit to 64-bit, you’ll have to perform a clean installation, which means buying a copy of Windows 10.

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