I just got a old mac from someone, It is a mid-2007 24 inch imac, with a Core 2 Duo 3ghz and 4gb RAM. It is, however, running OSX 10.4.11 Tiger. I have a install el capitan.app, but it wont install for some reason, and if i hit option while starting, only the HDD shows up. I also have a Yosemite DMG but idk if it works. I need this mac to run Captian