5.4-RELEASE Athlon64 E3/E4 core support

[Ryan R.]

First off, some info about my setup:

Motherboard: DFI Lanparty SLI-DR, nForce4, socket 939
CPU: Athlon64 3700+ "San Diego" core, revision E4, socket 939, 1mb L2 cache
Memory: 2x 512mb OCZ Value VX
I've run prime95 in Windows for just over 84 hours, with zero errors. 
I've run memtest86+ for about 12 hours, with zero errors.

Now, the problem is that I recently upgraded to this system from a socket
754 "Clawhammer" (C0 revision) setup, which worked perfectly in
5.3-RELEASE/amd64.  Before I upgraded the hardware, I didn't think to
rebuild the kernel/world with a clean make.conf and kernel config.  When I
booted the new machine, I got a kernel panic (fatal trap 9) on boot,
between the detection of my drives and mounting root.  I tried a few
things to get it working, but to no avail.  I then decided it has to be my
old world/kernel, so I did a binary upgrade to 5.4-RELEASE/amd64.

After doing the binary upgrade, the system would boot again (at first,
anyways).  Once the system had booted, I figured I should rebuild my
ports.  While I was watching the build, the kernel paniced again (I forgot
the exact message, and I didn't copy it down).  I once again tried a few
things to get it to work, but since I had spent so much time trying to get
it to work before the binary upgrade, I figured it'd be easier to just
wipe the drive and start over fresh, that way I have a known good system
to start with if any problems pop up.

So, I wiped the drive, and installed 5.4-RELEASE/amd64 on it.  Install
went fine, system booted, but then the panics came back.  It usually
happened while building some ports, but it happened in a different spot
each time, so it's not like one specific port was causing me problems.  It
also didn't happen only under load.

Now, I have the problem narrowed down to one of two things:
1) The hardware is bad.  This lead me to run the memtest/prime95 tests,
but they revealed no problems.  This leads me to option 2.
2) The amd64 build of FreeBSD.

So, I once again wipe the drive, but this time I install 5.4-RELEASE/i386.
 It installs fine, and boots fine.  One thing I notice during boot, is
that SSE3 isn't detected by the kernel as a CPU feature anymore (amd64
build did detect it).  I begin building all my ports, and I was able to
get my system up and running without even a hint of trouble.


So, I'm curious to know if there are any problems with the amd64 release
with these E3/E4 revision CPUs, maybe relating to the SSE3 instructions? 
Is there anything I can try to narrow down what exactly is causing my
hardware to panic?  I know I should build a kernel with debugging support
(I tried it before installing the i386 release, but got a kernel panic...
go figure), but I probably wouldn't be able to see the problem in a trace
if I tripped over it.

Any help would be appreciated.  Thanks.