Why not PCI crossfire or SLi?

[wyz135]

There's something I was very puzzled, every Motherboard have quite a lot of PCI slots, since now we don't use it quite often, why can't use ATi Crossfire or Nvidia SLi Multi GPU through PCI, and what if I really do so, installing more than one PCI graphic card on the same motherbard what will happen?

[Radiator]

You can't fit PCI-e cards in a PCI slot . That's why .
Also , the PCI bus is VERY slow compared to AGP/PCI-e .

[wyz135]

but there are PCI graphic cards like Radeon x1300

[Radiator]

Those are for the computers that don't have AGP or PCI-e slots . The PCI bus is MUCH slower than the AGP slot . The PCs with PCI slots only aren't gaming PCs .

[Mike]

They used to have them back in the day, but video cards got about 10 times faster and the PCI bus stayed the same speed and video cards pretty much just outgrew it. That's why AGP was invented, and it's why video cards are the only thing that takes advantage of PCI-E x16 slots today.