Q: no video at boot-up

[T. WATKINS]

Hardware guru's:
In making new box with:
Biostar M7VIB m/b; Duron 1.2 GHz; 256 Mb DDRAM; Aopen TNT2 (32 Mb) 
video; cheap case
(300 W p/s);  all new components.
At power on:
Unit beeps twice, but does not display video--not even POST flashing cursor;
Use lights on DVD drive and CDR flash; [floppy light shines if reset 
with medium inserted].
However, the CDR & DVD light even if ribbon cables are disconnected from 
m/b.
Could the power supply main output to the m/b be no good (though small 
leads to DVD, etc. may produce)?
Another Biostar m/b (w/RAID) & DDRAM has worked fine for me.
Any suggestion appreciated.
Tom