Windows 10: Will your PC run it?

How to upgrade an old PC to Windows 10 - free

The Windows 10 Technical Preview has been out for some time now, which means that it won't be long until the Windows upgrade cycle kicks into high gear once again. But if my inbox is anything to go by, a lot of readers are still confused as to whether their existing hardware will allow them to make the leap to Windows 10.

I'm not surprised people are confused. There's a lot of well-meaning yet inaccurate information out there written by people who don't really understand what makes PCs tick. It's understandable because tech can be confusing, and the Windows 10 system requirements throw a few curve balls into the mix.

The basics

OK, so what do you need to run Windows 10? Well, fortunately for us, Microsoft has already published the system requirements for Windows 10. Fire that page up because I'm going to step through the important bits of this document.

First thing that should pull your attention is this:

"Basically, if your PC can run Windows 8.1, you're good to go. If you're not sure, don't worry--Windows will check your system to make sure it can install the preview."

This is an oversimplification (we'll get to why in a moment), but it's a useful one nonetheless. Basically, most people running a Windows 8/8.1 system are good to go. And if you're not sure, the installer will run a check to make sure before trying to shoehorn the operating system onto hardware it's incompatible with.

So, what if you're not running Windows 8/8.1? How can you decide if your hardware is up to the challenge of running Windows 10? This is where the hardware specs come into play.

Here's what Microsoft says you need to run Windows 10:

• Processor: 1 gigahertz (GHz) or faster
• RAM: 1 gigabyte (GB) (32-bit) or 2 GB (64-bit)
• Free hard disk space: 16 GB
• Graphics card: Microsoft DirectX 9 graphics device with WDDM driver
• A Microsoft account and Internet access

Beyond the basics

Now if you're the sort of person who is a walking encyclopedia of tech trivia, then you might notice how these specs are the same as those for Windows 7. But there is one gotcha that you need to be aware of, and this only becomes apparent if you pull up the specs for Windows 8/8.1 and look closer at the processor specs:

• Processor: 1 gigahertz (GHz) or faster with support for PAE, NX, and SSE2

So in order to be able to run Windows 10 (or Windows 8/8.1), you need a processor that supports PAE, NX, and SSE2. Without this, your Windows 10 fun comes to an end.

Microsoft offers a handy primer on what these mean.

• PAE gives 32-bit processors the ability to use more than 4 GB of physical memory on capable versions of Windows, and is a prerequisite for NX.
• NX helps your processor guard the PC from attacks by malicious software.
• SSE2 is a standard instruction set on processors that is increasingly used by third-party apps and drivers.

There's more technical information on these features here.

Testing

So, how can you tell if your processor supports all of this? There are a few ways:

• Download and run the Windows 8/8.1 Upgrade Assistant. If your hardware is not up to spec, it'll tell you, saving you gigabytes of downloads.
• Try installing Windows 8/8.1. If it won't work, the installer will tell you before you wade out beyond your depth.
• Download and run a handy utility called CPU-Z. Look under Instructions and if you see SSE2, EM64T (indicates the processor has support for PAE) and either VT-d or VT-x (which is what's needed for NX support) then you're ready to rock.
  

• Manually check out your CPU by wading through this list. This will tell you directly if the CPU supports NX, and it will be listed as "NX / XD / Execute disable bit".

NX can be a pain in the behind because while your processor might support it, it could be disabled in the system BIOS, which then means having to dig around looking for the on switch.

To install a 64-bit version of Windows 8.1 (not Windows 8) on a 64-bit PC, your processor also needs to support CMPXCHG16b(which also, annoyingly, needs motherboard support, so it can be hard to test for), PrefetchW, and LAHF/SAHF, which adds more confusion. Fortunately, most people will have this already.

Some caveats

Remember earlier where I said that the "basically, if your PC can run Windows 8.1" bit was an oversimplification? Well, here's why. In the Windows 10 spec sheet is this line:

"Some PC processors and hardware configurations aren't supported by Technical Preview, including a small number of older, 64-bit CPUs, and some 32 GB and all 16 GB devices running a compressed operating system."

This is a Technical Preview limitation that should disappear once Windows 10 is ready to be unleashed on the world. However, it could stump some people trying to test out the preview -- specifically that "some 32 GB and all 16 GB devices running a compressed operating system" bit, which refers to devices such as the HP Stream 7 that run a compressed version of Windows 8. Some have claimed success in getting the Windows 10 Technical Preview onto such devices, but I wouldn't bother given the risk of something going wrong.

The virtual machine route

If you'd rather play with Windows 10 from the comfort and safety of a virtual machine, you can either install it into something like VirtualBox (these instructions for OS X will work on Windows), Hyper-V, or something like VMware Workstation. It all seems to work well as long as your hardware supports virtualization and your system has the grunt to run two operating systems side-by-side.

You could also experiment with a native boot VHD, although this is a kludgy and possibly buggy route to take.

TL;DR

If you're running Windows 8/8.1 then you're probably good to go. If you're not then the installer will tell you. Beyond that, the older your PC is, the more likely you are to be outta luck. That said, testing for compatibility is easy.

Gallery: AMD's new high-performance, energy-efficient 'Carrizo' APU

See also:

• Lenovo promises to stop bundling crapware on PCs
• Mac OS X is the most vulnerable OS, claims security firm; Debate ensues
• Tech essentials for the office and when on the road
• Crapware: Why manufacturers install it, what you can do about it, and why it's not going to go away
• Parallels Desktop 10 now makes it easy for Mac users to download and run Windows 10 (for free)
• How to run the Windows 10 Technical Preview on a Mac, for free