1. The problem statement, all variables and given/known data Why is it impossible for Pentium 4 to work in a 32-bit PCI bus without loosing any functionality? After all, other computers with a 64-bit data bus can do transfers of 32, 16 and even 8 bits wide. 2. Relevant equations 3. The attempt at a solution I'm not sure what loss of functionality is being referred to here. Does it have to do with the fact that Pentium 4 has 36 address lines? Or that PCI has a relatively low clock rate (up to 66 MHz)? I don't have any idea. Thank you in advance.