XPS 400 power button blink amber (solved?)

working XPS 400 Pentium D cpu

replaced dvd rw and fdd

power button starts blinking amber

no POST

immediate thought: psu died on me or motherboard died on me?

had a old XPS 400 psu die in front of me before.  try a differen psu, no more blink, but still no POST

replaced cmos battery, reset cmos jumper

no avail...

I disconnected dvd and fdd, POST again

connect DVD back, still post.

so the bad one is the fdd