A friend sent me a mail that in order to install windows 8 that my pc needs to support PAE, NX, and SSE2. Pls can anyone tell me what these mean and why they are required to install windows 8?

2 Answers 2


These are processor requirements

If you want to run Windows 8 on your PC, here's what it takes:

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

  • RAM: 1 gigabyte (GB) (32-bit) or 2 GB (64-bit)

  • Hard disk space: 16 GB (32-bit) or 20 GB (64-bit)

  • Graphics card: Microsoft DirectX 9 graphics device with WDDM driver

Also see:

What is PAE, NX, and SSE2 and why does my PC need to support them to run Windows 8?

Physical Address Extension (PAE), NX processor bit (NX), and Streaming SIMD Extensions 2 (SSE2) refer to features of the processor. PAE enables 32-bit processors to access more than 4 GB of physical memory on capable versions of Windows and is a prerequisite for NX. NX allows the processor to help guard the PC from attacks by malicious software. SSE2 (a standard on processors for a long time) is an instruction set that is increasingly used by third-party apps and drivers. For Windows 8, for your malware defense features to work reliably we require that your processor support NX. To enhance the reliability of third-party apps and drivers running in Windows 8, SSE2 is also required. If your PC doesn't support PAE, NX, and SSE2 you won’t be able to install Windows 8. Upgrade Assistant will provide you with an error message if your processor doesn't support PAE and SSE2. You'll also see a notice if the processor might not support NX or if NX is turned off in the PC BIOS. Windows 8 Setup will attempt to turn on NX during installation and, if it isn't able to, will return your PC to the current operating system.

You can check if your processor supports NX and can turn it on if it is turned off by going into your PC's BIOS. Accessing the BIOS can vary depending on your PC manufacturer. Usually, you must press a key (such as F2, F12, Delete, or Esc) or a key combination immediately after you turn on your PC before Windows starts. For more information, check the information that came with your PC or go to the PC manufacturer's website. Once you are in the BIOS, look for the NX or XD settings under the Security tab to turn on the NX support. If the BIOS setting for the NX support option is not available on your PC, you might need to contact the PC manufacturer for info on updating the BIOS. If you need help accessing the BIOS on your PC or turning on NX, you can contact support.

Source of information


NX means No Execute. It means that your CPU knows how to make parts of memory safer by provent programs from executing code in that part. Your CPU needs to support it and it needs to be enabled. (e.g. you can often turn this off in the BIOS).

SSE2 means that you CPU understands the second set of Streaming SIMD Extensions. These are instructions added to most CPU's since 2001. Windows 8 will use these. If your CPU lacks them then win8 will not be able to run.

PAE is a completely different game. A traditional 32bit CPU uses 32bit addressing. Both internally for data and on the address bus. With 32 bit it can address up to 232 memory addresses (that is 4G). PAE allows the CPU to address up to 36 bits of memory.

Think of it as two squares where you enter a page number. E.g. page "01", "02", .. "99". With only two numbers you can select up to a 100 pages (00 to 99). PEA is like adding a book number in front of it, allowing you to read pages 00 to 99 in book 1, pages [1]00 to [1]99 in book 2 etc. (But the books themselves (e.g. the programs) are still limited to 99 pages.

This is an artifact of 32 bit computing. If you have a need to use 4GB or more then please install a 64 bit version.

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