When considering an upgrade of the motherboard, or when intending to buy a new PC,
most people don't take into consideration the SYSTEM BUS.
Before buying a video card, the system bus has to be taken into consideration.
Getting better performance out of a video card and accelerator does not rely solely on the amount of VRAM it has.
A high-speed bus will enable better and faster use of the attached peripherals: video card, hard-disk controller, and network controllers.
A high speed bus would be:
Both PCI and VLB busses and expansion slots give the peripherals 32-bit direct access to the CPU.
To put this in simpler words: data can be transferred at the same rate as the CPU's clock speed,
while the 'old' ISA bus has a speed limit of 8 MHz.
Assuming the card is made for a local bus slot, its performance will be no less than 4 times better (and faster)
than the same card in a 16-bit ISA slot.