Just a thought on very old hardware, systems from around 1995 came with small power supplies and you could easily overload them by adding extra HDD or CD drives most of them in my experience were under 200W, I have seen some with as little as 75W. Its just something to keep in mind if you decide to go for more storage space. A little more info such as brand and model of computer might help, info on bios type, as there may be a bios update that could be done to get cd to boot if it is an issue.
“I have not failed. I’ve just found 10,000 ways that won’t work.” - Thomas Edison