Connecting 2 Hard Drives

Hello,

Im trying to hook up 2 hard drives to my pc. the first is a 8 gig and the second is a 4.3 gig. When i hook them up they wont fire up unless the IDE cables are unhooked from them.
NE thoughts u have would b gr8ly appreciated.
plz reply ASAP
thx
lil’ Frog

p.s. i dont no how many points to give so i just did 225.