Old computer bits (Hermitage RG18)

Hi, I'm resurrecting an old late 1990s PC. Does anyone have an old IDE hard drive that is smaller than 8Gb in size? Either 2.5" or 3.5" format will do. The motherboard bios will not take a larger size and I cannot get it to boot from a flash card. I also need some power cables for 3.5" and 5.25" drives. An old or broken psu would do for those. Many thanks.