It's basically 180 degree's off. With a straight through cable that has all the conductors/pins active, it would work but some cables have one pin that is disconnected. I've read that some DVD-roms like to be set to master but since you are using one IDE channel, set the hard drive to master and dvd to slave, then go into the bios and set the IDE primary master to "auto" and IDE primary slave to "disabled" or "none".