[Agorima]

Here I am explaining why you can't install the new Windows 8 on many Pentium 4 and Athlon 64 processors.

The first limitation introduced in Windows 8 is the Physical Address Extension (PAE) requirement.

While you can install Windows XP, Vista and 7 on the original Intel Pentium for testing purposes, the PAE was implemented first in the Intel Pentium Pro in 1995. Therefore this first limitation make the older Pentium too obsolete to install Windows 8.

The second limitation introduced is the Streaming SIMD Extensions 2 (SSE2) requirement.

It was introduced with the Intel Pentium 4 in late 2000. This limitation make the Intel Pentium II, III and their AMD competitors of the late 90s and early 2000s too obsolete to install Windows 8.

The third limitation is the Never eXecute (NX bit) requirement.

It was introduced around 2003, but since at that time many processors were sold without this technology, many Pentium 4 and Athlon XP are too obsolete to install Windows 8.
At the software level, it was implemented from Windows XP SP2 and Windows Server 2003 SP1.

Therefore, Windows 8 can be installed if you have a processor from about 2004 or newer.

This post has been edited by Agorima: 24 August 2012 - 05:13 PM

[Tripredacus]

"Install" is a relative term. I presume you are referring to Setup.exe.

But this makes me wish I had a Pentium 4 lying around to drop an image onto it...

[Agorima]

Tripredacus, on 22 August 2012 - 07:54 AM, said:

"Install" is a relative term. I presume you are referring to Setup.exe.

But this makes me wish I had a Pentium 4 lying around to drop an image onto it...

Yes. Probably there will be a way to bypass these requirements, just like the Ram.
When I had an Asustek L8400C with 128 MB of Ram, it was easy to modify the "Winsetup.dll" and install Vista and 7 Pre-RC onto that notebook, using vLite.
At that time I was lucky to have a notebook from 2001. It had the drivers for the 9x and NT OSes.
Good old times.

This post has been edited by Agorima: 22 August 2012 - 08:35 AM

[MagicAndre1981]

the Athlon 64 has all requirements (http://en.wikipedia....thlon_64#NX_bit) only the Pentium 4 will fail if it's not a Prescott version.

[Agorima]

MagicAndre1981, on 23 August 2012 - 05:14 AM, said:

the Athlon 64 has all requirements (http://en.wikipedia....thlon_64#NX_bit) only the Pentium 4 will fail if it's not a Prescott version.

My bad. I wasn't sure if the Athlon 64 has all the requirements.

[Shane]

It's the older Athlon XP processors that lack SSE2 support. All Athlon 64's have it.

[MagicAndre1981]

yes, but not all SSE2 CPU are compatible. My old Pentium M supports SSE2 but no NX Bit.

[Agorima]

Shane, on 24 August 2012 - 11:58 AM, said:

It's the older Athlon XP processors that lack SSE2 support. All Athlon 64's have it.

I'm changing the title of the topic. Instead of "Athlon 64" I'll write "Athlon XP".

[darqious]

Agorima, on 21 August 2012 - 03:51 PM, said:

The first limitation introduced in Windows 8 is the Physical Address Extension (PAE) requirement.

While you can install Windows XP, Vista and 7 on the original Intel Pentium for testing purposes, the PAE was implemented first in the Intel Pentium Pro in 1995. Therefore this first limitation make the older Pentium too obsolete to install Windows 8.

Actually Vista and 7 requires an i686 (Intel Pentium Pro) or RISC86 (AMD K5, no PAE capabilities). Original Pentium/PMMX can run none of these OSes.

[Shane]

I doubt that 8 really even needs NX to function, it's probably to enforce a minimum standard of security.