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I have a new Computer with Sandy Bridge CPU, which supports the new AVX instruction set, and Win 7 Ultimate x64 - which is supposedly capable of supporting AVX (i.e., 256-bit SIMD instructions/context-switch saving of YMM registers). The question is: is there any easy way to check whether this is enabled (non-programatically)?

Edit: If it is not enabled, what is the procedure to enable AVX support by the OS?

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up vote 2 down vote accepted

According to Microsoft this will only be supported under Windows 7 Service Pack 1 (slightly offtopic but factual) which is due out this month. I can't find any detail as to enabling/disabling it - I assume it'll be on by default and your code needs to be written to use it. Maybe somebody else will have some insight on this?

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That would make sense. I wasn't aware of the fact that the current version doesn't yet support it - I programatically checked for AVX support and realised it's set to off, and my initial interpretation was that it was a bug in my code. Thanks. – random Feb 10 '11 at 21:01

To enable or disable AVX instructions you can use this commands:

Enable AVX: bcdedit /set xsavedisable 0

Disable AVX: bcdedit /set xsavedisable 1

Open your command prompt and type it, then hit the enter button.

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