A new reference motherboard design
The nForce 780i SLI comes with a new reference motherboard design that will be brought to market as-is by some of Nvidia's partners. Larger motherboard makers like Asus, Gigabyte, and MSI tend to spin their own board layouts. However, Nvidia's reference designs have been popular with XFX, EVGA, BFG Tech, Foxconn, and even ECS. We used an XFX 780i SLI board for testing and have a second board from EVGA that's essentially identical.

Overall, the board layout hasn't changed much since the nForce 680i SLI, which isn't necessarily a bad thing. Nvidia has managed a layout that is packed, but not crowded, with most of the connectors in just the right place.

Take the board's power plugs, for example. Both the primary 24-pin connector and the 8-pin auxiliary 12V plug are located along or near the top edges of the board to allow for cleaner cable routing within traditional ATX enclosures.

Things have changed a little around the socket, where a brand new cooling array covers the chipset's SPP and MCP components, the nForce 200, and the board's voltage regulation circuitry. The chunky cooler is actually less elaborate than the twisted heatpipe networks we've seen on some motherboards, despite the fact that it has an additional chip to cool in the nForce 200. There's plenty of surface area, though, and the heatsinks are carefully shaped to provide clearance for larger aftermarket CPU coolers. Even Scythe's massive Ninja heatsink will fit on this board.

We had no problems running the 780i SLI reference board at stock speeds with passive chipset cooling, but for overclocking, Nvidia provides an auxiliary fan that snaps onto the north bridge cooler. This fan plugs into the motherboard, and its speed can be controlled through the BIOS. The fan is pretty loud, though, so you'll want to avoid using it if you can.

On an open test bench with a single graphics card installed, the fan was only necessary once front-side bus speeds started to approach 450MHz (or 1800MHz, quad-pumped). However, we've also observed the need for additional chipset cooling with SLI configurations, so you might have to bust out the fan for multi-GPU systems, as well.

Moving south, the 780i's chipset cooler covers the south bridge with a low-profile heatsink that won't interfere with longer graphics cards. Nvidia has also done well to ensure that none of the board's Serial ATA ports will be blocked by longer or double-wide graphics cards. Even with a trio of massive cards installed, you'll still have access to all six of the board's SATA ports and even its IDE port, too.

One minor change for the reference design is the location of the board's front-panel connectors. On the 680i SLI reference board, these connectors were oddly located up by the DIMM slots. The 780i, they've been moved to a more traditional location in the bottom right-hand corner of the board (bottom left in the picture above). There, the front-panel connectors are joined by onboard power and reset buttons and a handy two-digit POST code display.

Three-way SLI compatibility calls for a trio of PCI Express x16 graphics slots. Only the top two slots are PCIe 2.0, with the third hanging off the south bridge's first-generation PCI Express implementation. You also get a couple of standard PCI slots and one PCIe x1 slot.

With three double-wide graphics cards installed, there won't be room for any other expansion cards. Fortunately, such configurations are likely to be uncommon. Even with a two-way SLI config, you'll still have access to standard PCI and PCIe x16 slots. And because PCIe slots are backwards compatible, an x16 slot can also handle x8, x4, and x1 cards.

Little has changed around the 780i SLI's port cluster, where you'll find a pretty standard array of expansion ports. A full suite of analog audio ports make an appearance fed by Realtek's ALC888S codec chip. You get a TOS-Link digital audio output, too, but no provision for digital audio input or coaxial output.

Six USB ports make an appearance here, with the remaining four accessible via onboard headers. An additional Firewire port is available via an onboard header, as well, with both fed by a Texas Instruments TSB43AB22A chip that hangs off the PCI bus and supports 1394a "Firewire 400" speeds.

The only glaring omission from the port cluster—apart from serial and parallel ports that perhaps only half a dozen folks will actually miss—is external Serial ATA connectivity. eSATA enclosures aren't overwhelmingly common just yet, but with eSATA ports available on just about every high-end board, they should really be included here.