Components of a pc like
processor, RAM, disk, and others need to talk to each other. The system that
connects these components is called IO. Hard
drives, peripherals, LAN cards, sound cards, USB, and firewire all pass data
through the same I/O system as your first 486 PC; the PCI bus running at
33mhz and shifting 133MB/s of data.
Hard
drives that are connected on the IDE interface can theoretically overload PCI. However
PCI express will leave much speed for these devices removing the IO speed
bottelnek.