My first "PC" was a Z80 1MHz, 1KB. This got upgraded to 16KB My second "PC" was a 6502 2Mhz, 32KB. This got upgraded to 4Mhz and 48KB. My third PC was 486DX 25Mhz. This got upgraded to 66Mhz, then upgraded to 586 P60. Yes, the CPU was on a card (Compaq Deskpro M days) and the processor card could be swapped! The P60 then got upgraded to a P233MMX (?) via a socket 4 to 7 converter! This BEAST used to play DOOM very fast, together with a Matrox Millenium. The SAME machine then got upgraded AGAIN using a AMD K6-III. It was very very expensive... and imported from Singapore. The cache on this thing made if FLY. BUT... the CPU burnt out after a few days of use. There was no "thermal" control... and like MANY OTHER PEOPLE, I suffered my very first CPU failure through a AMD K6-III fry. I have never bought AMD since. I know many people swear by AMD today... but people like me who were early adopters got burnt (literally) and went straight back to Intel.