Comment 2 for bug 783239

For what it's worth, the latest microcode update seems to be the one dated 2011-04-28 (DwnldID=20050) as available at
http://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=20050
(or at hxxp://downloadmirror.intel.com/20050/eng/microcode-20110428.tgz bypassing the license screen).

Manual instructions as a workaround:
Downloading this archive and extract the microcode.ctl file it contains, then store this file at /usr/share/misc/intel-microcode.dat (optionally after moving the previous version out of the place). Then optionally run "microcode_ctl -u" to apply (or reboot).
This file, microcode_ctl and a hook to execute microcode_ctl should probably be included in an initrd so that it is loaded early in the boot process (but this is really beyond this bug report).