not necessarily. Not all mac hardware is from apple. You would just need to make sure the hardware you buy, is designed to work with Macs. There are several companies that make processor upgrades for Macs that have no relation to Apple, they just bought the rights to use the G3/G4 architecture from Motorola and then sell you their version of that processor. And the same thing with Ram and HD's and Vid cards. My iMac's custom Ram came from Viking memory inc. and my new HD came from Maxtor. and the Vid card is from ATI. The optical drives are also non-apple.
