Question

Q: Windows 8.1 refuses to install on AMD Opteron because it don't support CMPXCHG16b (CompareExchange128). This thread is locked from future replies

Hello!

I have this error when trying to install Windows 8.1 on my AMD Opteron PC: 
"You can't install Windows 8.1 because your processor doesn't support CompareExchange128."
This happens with both preview and the final release.

I wanted to ask what has changed between Windows 8 and 8.1 because Windows 8 works perfectly good on my PC.
Looking for some internet proof to this behavior.

Thanks!
Elad.



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Hi Elad,

 

1.    How are you trying to install Windows 8.1?

2.    Are you trying to install Windows 8.1 on VirtualBox?

3.    How did you install Windows 8 on the computer?

4.    What is the model of the computer and the processor?

 

Please provide more information to assist you better.

Asking an effective question to get help quickly

http://answers.microsoft.com/en-us/windows/wiki/windows_other-system/asking-an-effective-question-to-get-help-quickly/18584631-7f2b-4f01-88f5-f6660a5943c3

Rohit S

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i'm having the exact same problem. opteron 170, socket 939.

 

I figured MS would remove this limitation by the RTM stage?!?

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I have the same issue as well on AMD Athlon 64 4000+

Windows 8 has worked fine but 8.1 refuses to install due to this issue.

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Hi,


Thanks for your reply!


Sorry for omitting basic info. Here it is:

1. Trying with USB drive or mounting the ISO. Same results. The update doesn't show up in the store.

2. Nope. Trying to install regularly.

3. I Installed Windows 8 From USB drive. Fresh install.

4. DIY PC, processor is AMD Opteron 185.


As the 2 replies above added, all AMD Athlon 64, FX, Opteron 1xx, 2xx and 8xx (as far as I could check) don't have CMPXCHG16b instruction set and therefor do not support Windows 8.1. Again, Windows 8 works perfectly.


In all versions up to Windows 8 (apparently) there was a workaround by Microsoft that was implemented in the OS (Software solution) to support 16bit compare (CMPXCHG16b) instruction set.

I wanted to know why it was omitted from Windows 8.1 and what are the benefits of removing such workaround.


I was looking for some blog post, a KB article, something to ease my mind.


Of course those systems we are using are 8 years old by now and dropping support for them was an inevitable move that was bound to happen some day. I just didn't expect it do come with a minor version upgrade!


Thanks!


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now that we have provided hardware details about our systems, i was expecting some kind of reply or at least official position from microsoft, regarding the drop of support for amd k8 processors?!?!

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My system with Windows 8  running on AMD Athlon 64 4000+ had the same issues.  I  read in another thread on a different site that 8.1 will only work if installed as 32 bit on these older processors.  It's a shame,  but worth considering. 

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Update: I tried now Windows Server 2012 R2 and it didn't have this restriction.

 

 

 

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did you install the 32 bit or the 64-bit version?

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Actually I didn't install it yet, just ran the installer.

It didn't show the same error as Windows 8.1 did.

 

Windows 2012 R2 comes only in 64 bits version...

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Actually I didn't install it yet, just ran the installer.

It didn't show the same error as Windows 8.1 did.

 

Windows 2012 R2 comes only in 64 bits version...

yup i can confirm.

obviously server 2012 r2 is a different animal to windows 8.1 (and 8.0 for that matter).

still waiting for a reply, microsoft!

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Question Info

Views: 8172 Last updated: January 7, 2018 Applies to: