A recent Planet Analog article, Non-correlation of Peak Noise and Peak Current, discussed the complexity of reactive and resistive noise that combine to form dynamic voltage drop in a chip power grid.
5.25" slot-loading DVD drives are almost non-existant now so I reckon your only option is going to be to get a slot-loading notebook drive (like the OptiArc AD-7630A) and then an adapter so you can ...
Buy a slot one, I always worry that some day I will do something stupid and break the tray off my CD-ROM. But internally, they're the same, so go with your preference.