NVIDIA debuted its SLI technology as the PCI Express interface appeared and the AGP interface would simply not be enough for an effective SLI system. This may be true but that doesn’t mean that it’s technically impossible to run SLI with the AGP interface, not even when using an AGP graphics card together with a PCI Express graphics card. This has namely been achieved at OC Workbench, where they’ve turned to motherboard manufacturer ASRock and chipset manufacturer ULi which are both known for its odd solutions. ASRock 939Dual-SATA2 is equipped with both AGP and PCI Express slots which with the right drivers seems to support SLI with the two interfaces.
At OC Workbench they’ve published benchmarks and a number of screenshots with the system using two Leadtek Winfast GeForce 6600GT graphics cards, one PCIe and one AGP. There is no single card figures for comparison though but the most important here is that SLI work, even when using an AGP graphics card. Whether this is a commercially feasible solution or not, is a completely different matter.
