NVIDIA SLI Multi-GPU technology is enabled through PCI Express
and the technology is currently under Patent Pending. The SLI connector can be
found on top of the NV45 card and a SLI link card is needed to link up two NV45
cards. Only two identical graphics cards with the same core speed can be used,
in this case either 2 x GeForce 6800 GT or 2 x GeForce 6800 Ultra. David Kirk
mentioned that NVIDIA is considering to offer the SLI Multi-GPU technology to
other GeForce 6 series as well. The circuitry on the link card is rather simple
although it is a high-speed digital link between the two graphics cards but the
bandwidth is not known to us yet.
Certainly a PCI Express based motherboard with two PCI Express
x16 slots will be needed to support two PCI Express graphics cards. However,
only one x16 slot will have full x16 bandwidth while the other x16 slot has x8
or x4 bandwidth. So far only two manufacturers have produced Tumwater boards
that offer two PCI Express x16 slots; IWILL and now Supermicro with their X6DA8.
We have first seen Alienware demonstrated their Video Array-enabled ALX systems
at E3 this May using their X2 board, a Tumwater based OEM motherboard from IWILL.
However, IWILL has made clear to us that this board won’t be available for
channel/retail market but only exclusively for Alienware. TYAN too has plans to
offer Tumwater based board that offer two PCI Express x16 slots depending on
market situation and demand.