I get the reason of FreeBSD 8.0-BETA2/amd64 crashes on SMP under load

I think I get the reason of FreeBSD 8.0-BETA2/amd64 crashes on SMP under load.

I have two machines

1.
AMD Athlon 64 X2 5000+
Jetway HA07(AMD 790GX+SB750)
Kingston 4GB DDR2 800
ITE 8212 IDE RAID
Maxtor 80G IDE
WDC 500G SATA

2.
AMD Phenom II X3 710
Jetway HA08(AMD 790GX+SB750)
Kingston 8GB DDR3 1333
WDC RE3 1TB*2(RAID1)

Both 1 and 2 set SATA mode in RAID in BIOS.

When I install FreeBSD 8.0-Beta2 on 2, it always restart, installation can't begin at all..
3 days ago, I had an idea to install FreeBSD on 1.  First I use 7.2 AMD64, and 1 normally started the installatiion, when I used the RAID1 attached to 1, it can't search my raid1 disk. When I changed the disc to 8.0-beta2 AMD64, it can normally started the installation also, but it just can recognize two seperated disk, can't recognize the RAID1.

The mainboards both used AMD 790GX+SB750, So I thougt the reason of FreeBSD 8.0-BETA2/amd64 crashes on SMP under load is FreeBSD 8.0-beta2 Amd64 can't support Phenom II. But I can't understand why 8.0-beta can't recognize the RAID1. Please answer me.
guhi.zhang 
2009-08-13