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I have installed a Microsoft Hotfix update from 2011 that rectifies something in mcupdate_GenuineIntel.dll.

I also checked SiSoft Sandra to ensure that supplied in BIOS is latest, from 2013.

My question is: since Microsoft microcode update loads after BIOS, is OS smart enough to let the newer microcode run, or does it fall back to 2011 microcode?

And just in case this question cannot be answered directly:

A common way to tell would be to try some code that fails with older microcode but succeeds with newer one. Does Intel publish such code snippets?

EDIT I was able to verify that Microsoft has pushed out a newer Intel CPU microcode update to this PC:

C:\Windows\System32>dir *genuine*.dll
 Directory of C:\Windows\System32
05/09/2015  12:26 PM           493,504 mcupdate_GenuineIntel.dll
GregC
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OS doesn't need to be smart enough to let the newer microcode run, CPU will run whichever is the newest. Yes OS microcode loads after BIOS but CPU will reject OS's microcode if the BIOS's microcode was a newer version.

If BIOS's microcode was older and OS's microcode is newer than CPU will accept OS microcode and will run the newest version. So it's up to CPU and OS doesn't need to do a lot of checking. CPU will always run the newest version available.

justsomeguy
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