Building your own PC is a very difficult but rewarding process. While putting all the circuit boards together, you will need to purchase a Molex connector or two to connect different components inside the PC. These connectors come fully assembled, but if you want to learn how they fit together, you can purchase a Molex connector kit. This kit allows you to assemble a connector to go to a power supply, disc drive, or other components. For the hard drive, you would create a 4-pin Molex connector. Graphics cards also use a 4-pin connector. Components such as power supplies use either 20- or 24-pin varieties. When buying or creating your own Molex connector, make sure you know what type and configuration each PC component uses to make installation go smoothly without using trial and error. When you purchase your supplies from reliable sellers on eBay, play it safe by choosing a bulk package of connectors or a larger kit just in case you make a mistake or forget about that extra connector you need.