Usually, even with all that stuff, a decent 300 watt power supply would suffice. I say decent because a lot of generic cases have crapola power supplies made by L&C technologies and other fly-by-night companies. Frankly, these power supplies are dangerous. I've had several of them literally blow up. Inside, capacitors exploded. On one occasion almost causing a fire.
You could also try updating the latest BIOS.
<A HREF="http://www.msi.com.tw/support/bios/bios.php?model=MS-6380+V2.0" target="_new">http://www.msi.com.tw/support/bios/bios.php?model=MS-6380+V2.0</A>
One other thing could be over aggressive RAM timings. You could try backing them down a bit. But more than likely it's your power supply. I have my K7T266 Pro 2 with the most aggressive settings and it works like a champ.
I can't think of a good signature so I'll use this one.