SOLVED: Windows 8.1 Will Not Install on Older AMD CPU’s like Athlon 64 and Opterton

If you have an older AMD CPU based system and you attempt to install or upgrade to  Windows 8.1 you will see a message like:

You can’t install Windows 8.1 because your processor doesn’t support CompareExchange128.

This is true but there are three important points to note:

1. 32BIT Windows 8.1 will install / upgrade
   1. of course you can NOT upgrade 64Bit Windows 7 or 8 to 32Bit Windows 8.1 but you could perform a fresh install
2. 32Bit OR 64 Bit Windows 8.0 WILL install / upgrade
3. APPARENTLY 64Bit Server 2012 R2 WILL install
   1. I have not tested this

The limitation on 64 bit Windows 8.1 applies to AMD Athlon 64 / Opteron 1, 2 or 8 series CPU on Socket 939 754 etc.

🙁

That being said I a THRILLED to get an amazing Alienware MJ-12 8550A running Windows 8.1 with NO extra drivers or utilities.  After the initial boot, I did a Windows update which caught the new drivers for the nVidia Go1400 card and a few other items.  Even the media buttons on the front of the ‘laptop’ plug and played.  It is running perfectly well.  AMAZING for a machine from 2006!