First of all I want to say that Prices doesn't matter to me!
I want to make a Super Computer, so I need to know which is the Best
Cabinate (Stylish), Motherboard (Best Performance), Power Supply (Supporting my Specifications), Processor (Best Performace & Powerful), Hard Disk (Best Performance & Fastest), RAM (Best Performace & Fastest), Graphic Card (Best Performance & Fastest), Sound Card (Best Performace), Optical Drive (Required)

You are asking us to do your legwork for you in researching. If price does not matter just buy an alienware computer. They are the best.

Generally all hardware parts are very important for super computer. But mainly Hard disk, motherboard and processor is very important hardware part for supercomputer because through this three hardware parts user can easily work with super computer.