Windows 8.1 64 Bit Not Working on Some Old AMD Processors

It has been revealed that the older versions of AMD processors might be useless with the latest Microsoft Windows 8.1 64 bit. This piece of information was recently revealed to Neowin by Microsoft itself when it stated that all the older AMD processors will face issues while trying to run Windows 8.1 64 bit. Some of these AMD processors have been named by Microsoft such as the elderly Athlon 64, Athlon x2 64 or the Opteron 185.


The CMPXCHG16b instruction set which is a requirement of the running of the Windows 8.1 64 bit is missing in all the older AMD processors and this is predominantly the reason why they will have trouble while trying to run the Windows operating system. These older processors worked with the 64 bit version of Windows 8 due to its ability to host the special software that made it possible but which has been discontinued now. People who have the older AMD processors can run the 32 bit version as that works perfectly and will pose no issues.

The reason why the special software feature was removed and Windows 8.1 64 bit didn’t extend support for older processors is that Microsoft wanted to increase the security level. The security was made more effective for Windows by removing the code which can no longer follow instructions such as the CMPXCHG16b instruction set.

Though many people will be so happy about this news but it is quite evident that the decade old processors should now be upgraded to newer ones.

Source: Neowin | News Archive