My older pc lga 775 not bios posting, need suggestions.

Hello all, I have a rebuilt hp dx7300M/E6300/250hnqm/1.0R/j s/n:HUB7251CNB that refuses to post. I checked psu interior, seemes fine, recapped MB board,most of 6.3v470uf were blown/bulged, however after pressing pwr buton, fan stops and 10 beeps appear+ orange led , manual says it's "Bad option card" whatever that means, I don't have any cards inside. Tested dx7300 with stock atx psu, or a pcie gpu... made no difference. Problem persists. I need some assistance, don't want to trow away the pc.