PC won't post when certain hard drives/combinations of drives are plugged in
 

I am stumped, I searched everywhere and tried a bunch of things to no avail, so I'm hoping someone would know the answer. I have a pretty old PC with an Asus A8N SLI Deluxe motherboard that I’m trying to give a second life to. There are a total of 7 hard drives inside – 4 SATA, 3 IDE; one Asus...