K, Question : Was your old HDD SATA or IDE ? Also, is your CDROM SATA or IDE ? Because if your old HDD was IDE it probably would have been set as "Master" and the CDROM if IDE, would have been set as "Slave".
One thing I have found is if both drives on an IDE cable are set the same, i.e. either "Master" or "Slave", then the computer won't recognize them.
Things to check : 1) check the "Master' "Slave" setting for all IDE devices in the machine. 2) Check and make sure that all the cables for said devices are properly plugged in. This because sometimes the plugs don't seat properly, and you get problems on account of that. 3) This is particularly true of SATA devices, because SATA cables are fairly stiff, but they don't plugin very firmly, so if there is a BEND in the cable near where it plugs in, they tend to UNPLUG themselves.
If that proves to be the problem, what I have done for a friend of mine, is work a bend into the cable, where it has to bend, so as to have it accept that shape, so it doesn't UNPLUG itself.
Hope that helps.
Edited by JHMcG, 06 July 2013 - 03:22 PM.