# Windows 8.1 Update error: CPU not supported?



## Bonecrusher123 (Apr 28, 2007)

Hi all, I've got a Q9400 here and I just tried installing Win8.1, but I'm getting this error:

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

I can't change the CPU so what can I do? I don't understand why my CPU isn't supported and this sucks because I bought Win8Pro recently...


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## dai (Mar 7, 2003)

i assume you are referring to 64x win

you may have to run 32x win


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## TerryNet (Mar 23, 2005)

For more on what dai is saying see Solved: Windows 8 OEM.


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## Bonecrusher123 (Apr 28, 2007)

Yah I'm using 64bit Win8 Pro. There's no way I'm going to 32bit... since I've got 4.5GB of RAM + my video card. The Q9400 isn't even that old.


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## Bonecrusher123 (Apr 28, 2007)

Anyone???


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## Bonecrusher123 (Apr 28, 2007)

I'm running team viewer if that makes a difference.


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## TonyB25 (Jan 1, 1970)

Google search results mostly include references to VirtualBox. Are you trying to install Windows 8.1 in a VirtualBox guest machine?


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## dai (Mar 7, 2003)

your cpu does not support 8.1 64x


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## Bonecrusher123 (Apr 28, 2007)

dai said:


> your cpu does not support 8.1 64x


Huh? I just bought Win8 Pro as well... Will Microsoft release a fix?


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## dai (Mar 7, 2003)

probably their fix will update the cpu


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## Bonecrusher123 (Apr 28, 2007)

What do you mean?

Do you have a link saying that the Q9400 isn't supported?


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## dai (Mar 7, 2003)

http://answers.microsoft.com/en-us/...mpatible/d0a08d02-4f17-4581-8f39-3d71fc737eb8


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## Bonecrusher123 (Apr 28, 2007)

Okay, this sucks. A lot. 

Will I be able to upgrade to later versions of Win8 64bit?


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## dai (Mar 7, 2003)

i doubt it

only my opinion ms don't include me in their f/ward planning


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## Macboatmaster (Jan 15, 2010)

Post 7 may provide a clue on this


> Google search results mostly include references to VirtualBox. Are you trying to install Windows 8.1 in a VirtualBox guest machine?


there appears to me to ne some doubt as to if that processor the Q9400 does meet the requirements of 8.1

What certainly appears to be correct is that many people have received the report you have when they have installed 8 on a virtual machine - EVEN if it has since been changed.

I have read the link provided by my colleague *dai*
I have also found reports that the 9400 does meet the basic requirements.

There is ONE most certainly definitive source for an answer and that is INTEL


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## Bonecrusher123 (Apr 28, 2007)

Is there a solution for this yet?


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## TonyB25 (Jan 1, 1970)

Your processor isn't supported. There's no fix.


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## dvk01 (Dec 14, 2002)

opened by request but there is no point. Your processor is not supported for W8 or W8.1 install in 64 bit but probably is in 32 bit versions 
The same will apply to theW10 preview and when it comes out the final version. 
You can make as much noise about it as you want, but Microsoft made a decision that W8 & newer OS will only install & work on CPUs with specified functions enabled. 
I was really annoyed when my Pentium D wouldn't work on W8 and had to go out and buy a new computer, despite the fact that everything else worked on it. 
I keep the old one on W7 for testing purposes


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