It has nothing with HDD, Xbox 360 use laptop version of HDD that's low heat and low watts, around 2.5 watts or so.
It was PPC (PowerPC) and ATI graphic, PPC use too much heat, that where Mac is used had PPC until Apple switched to Intel due heat issue, delayed of 3.0 GHz and no G5 chip for laptop.
I wish Xbox 360 will use Intel instead of PPC.
