FreeBSD 9.0 (RC2) Causes BIOS Message on Reboot

Thomas D. Dean tomdean at
Wed Dec 14 20:20:12 UTC 2011

I know, this sounds strange.

I have an ASUS P9X79 motherboard, Intel i7-3930K CPU.  The motherboard
TPU switch is on.

This overclocks the CPU to 4.162GHz.  Calculated from the TSC, with code
from Intel.  The details of doing this are in the CPUID datasheet.
sysctl dev.cpu.0 always shows freq as 3.201GHz no matter what the clock
actually is.

Often, when rebooting from FreeBSD, I get a message from BIOS that
overclocking has failed - press F1 to enter setup.  I press F1, exit
from setup, discarding changes, and the calculated CPU clock is
3.201GHz.  Overclocking has failed. 

I shutdown, cycle power, boot, and overclocking works, calculated CPU
clock is 4.162GHz.

If I save changes when exiting from setup, overclocking works.  A bus
reset is issued?

I have a tripple boot, Windows 7 for possible warranty issues, Linux and
FreeBSD 9.0(RC2).

I never see this message when rebooting from either of the other two
OS's, only FreeBSD.  I booted all three 5 times and saw 3 instances of
overclocking failed when rebooting from FreeBSD.

Here is the question:  How may I find out what is causing this?

I have an HP Envy 17 3D notebook that always has side effects of booting
FreeBSD 8.2 AMD64 where Windows 7 and Linux do not.  An over temperature
message 0090D.  The machine is not actually over temperature, just
something tweeked that BIOS sees.

Two machines doing strange things on reboot - it is not hardware or
BIOS, both different.


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