Well if you think the PIII is 900mhz then that raises some flags for me.
What is your ram speed set at? 100mhz or 133mhz FSB?
Cas settings? 2-2-2 or 3-3-3 Or 5/7 or 7/9?
I hope your not overclocking that to 900 .
1 more thing...
WHat are you using for your motherboard? Is the PS 60watts enough? <-- not enough watts...??? SuperMicro Motherboard? I have SuperMicro older Tower server case and most of the baords I knew back then used alot more than 100watts.
I think the pIII 900mhz uses 60watts alone. I think you should just get a Opus.