PATA (parallel- Advanced technology atachment) cables are used namely in the HDD, cd-roms and floppy disks in the old comps and are not used now days cause they have been replaced by the faster, smaller SATA cables which is nowdays being used in hdds and cdroms. While the molex cables power the fans, the gpu(using a converter) and someother extra components you may wanna add. Almost the same thing.