The majority of the servers in my closet are running intel processors (mostly P3’s). Apparently intel publishes microcode updates for its processors, which should supposedly improve the processor’s performance and/or reliability. I have no idea if it does improve anything at this point as Intel does not provide a changelog for the microcode. Gentoo has an ebuild for the linux microcode utility which you can setup to auto-upgrade you’re processor at boot. Microcode changes do not survive power-down, so they must be re-applied at boot.

Sep 21 18:00:26 sakuya kernel: microcode: CPU1 updated from revision 0x0 to 0x7, date = 05052000 Sep 21 18:00:26 sakuya kernel: microcode: CPU0 updated from revision 0xc to 0x13, date = 02062001

As you can see, there were quite a few revisions between my released P3 800’s and the published intel microcode. I’ll update this in a few weeks with my findings.