Did the optical drive you originally had, and that you are replacing, ever make noise and show signs of life? Are you using the same optical drive cable with all these drives? If your original drive showed signs of life, have you tried putting it back in with the cable you are now using in order to verify that cable is capable of powering a drive?
A drive that has no power and that is not taking in media is not going to show anything in system profiler (to answer Dan's comment).
If two drives in a row fail to get power, the common element is probably the hard drive cable, so I'd try another, or try the one that you used with your initial drive, assume that one had power. It's also conceivable that both drives are bad (I've seen far stranger things), however that would be unlikely because the vast majority of bad drives tend to power on yet fail to read discs.