computer keeps rebooting

[Adam Townsend]

I recently built a big big box to play around with, running VM's & Jails &
such, & test benchmarks & do whatever else I thought might be fun on a
computer.  I overclocked the processor a little (what's the point of having
a Black Edition chip if you don't?) & got it to run FreeBSD 7.2 amd64 stable
at 3.8 GHz, but when I bump it up to 4.0 GHz, I get thrown into a reboot
cycle.  It just reboots after it recognizes my hard disks, no kernel panic
or anything.  I'm using the GENERIC kernel & haven't started messing with
stuff (it's a clean install).  If I bump the processor back down to 3.8 GHz
it runs perfectly fine (ran it over 24 hours straight w/o any problems).  My
Motherboard won't let me overclock past 4.2, it throws an error in the BIOS
about it, so the hardware can handle 4.0.  Does anybody have any idea why
FreeBSD would do this?  It's not a big deal, I'm just curious.  Would there
be some way to capture what's going on?  I tried to save the core dump from
it, according to ch 10 of the developers handbook, but on the next
successful boot, there's nothing in the /var/crash directory.

Hardware:
AMD Phenom II x4 955 BE
*GIGABYTE GA-MA790FXT-UD5P AM3 DDR3 AMD 790FX ATX AMD Motherboard
**mushkin 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Dual
Channel Memory
1x Western Digital VelociRaptor 150GB HDD
3x Western Digital RE3 1TB HDDs
****SAPPHIRE 100245L Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16*
*
*Thanks,
Bucky