Verdict: With 3-Way SLI and Penryn support, XFX rolls out the big guns.
If the Green Goblin were to buy a motherboard, the XFX nForce 780i SLI would probably be at the top of his list. It's based on Nvidia's reference design, so the familiar black and green colour scheme is out in full force. The three lime-green PCI-E slots for 3-Way SLI certainly catch the eye, and the chunky chipset cooling and black PCB give the board a mean industrial look. As this board follows the Nvidia reference design, expect other 780i SLI boards from manufacturers typically associated with Nvidia graphics cards (such as BFG and Inno3D) to be remarkably similar.
The product name sounds like R2-D2's love interest, but it's still obvious that this is indeed a motherboard based around Nvidia's new high-end nForce 780i SLI chipset. It arrived just in time for our 3-Way SLI testing last month and we also carried out some tests on the board itself. However, even with three GeForce 8800 Ultras - roughly £1,200-worth of graphics hardware - we only just achieved a playable frame rate in Crysis at 1,680 x 1,050 with 2x AA. While 3-Way SLI may be of questionable value, though, you can use two-card SLI, and the new BIOS released since last month should bring the board up to scratch. Given that the XFX overclocked well last month, we wanted to find out how good the new BIOS is.
However, let's provide a little background before delving into the scores. The nForce 780i is Nvidia's answer to Intel's X48 chipset (the 'i' suffix denotes that this chipset is designed to support Intel CPUs, so AMD fans should look out for nForce 780a). Much like X48, it supports PCI-E 2.0. However, only the primary and secondary slots are PCI-E 2.0-compatible; the third slot is connected to the Southbridge and is only PCI-E 1.1, meaning that 3-Way SLI setups will revert to PCI-E 1.1 bus speeds rather than the faster PCI-E 2.0.
Another selling point is the nForce 780i's native support for Intel's new Penryn-based processors with 1,600MHz FSBs, such as the Intel Core 2 Extreme QX9770. However, bear in mind that even older chipsets that don't officially support these brilliant new processors should accommodate them. The Asus P5B Deluxe, which is based on the venerable P965 chipset, for example, can recognise a Penryn CPU after a BIOS re-flash and can easily overclock to a 1,600MHz FSB. Native 1,600MHz FSB support, therefore, isn't the knockout feature Intel and Nvidia would have you believe. However, motherboards that support a 1,600MHz FSB by default should overclock even further.
This XFX board sensibly has four DDR2 DIMM sockets for up to 8GB of memory. As it's an Nvidia board, you can overclock the FSB and memory separately - the 'unlinked' overclocking mode removes the need to use memory dividers and a calculator while overclocking. If you want to save some cash for multiple graphics cards, you can use basic RAM and hold it at its rated frequency while going as crazy as you can with the CPU's FSB.
The motherboard has a fan that clips on to the Northbridge heatsink, which XFX recommends using when overclocking or water-cooling to guarantee stability. This made us wonder why the fan isn't fitted as standard, especially as the heatsink quickly became roasting hot when we removed the fan.
Unfortunately, the fan is a whiny aberration and a step backwards in today's world of quiet vapour chamber cooling, and Intel and AMD's completely passively cooled motherboard chipsets. We suspect that the fan won't be necessary if there's plenty of airflow through your case, but we'd use some kind of direct cooling for the Northbridge in a cramped system. Whichever cooling methods you choose, be careful not to touch the hot copper heatpipes around the CPU socket while the system is under load, or you may end up with burnt fingers.
The sloping heatsink at least allows for a huge CPU cooler and plenty of room to fit it. Restrictive copper heatpipes and monstrous VRM heatsinks aren't part of the Nvidia 780i SLI reference design.
The bottom half of the board has six S-ATA II ports. However, to free up as much space as possible for three large Nvidia graphics cards, only two of these are well situated, next to the right-hand edge. The other four are squashed against the EIDE socket - if you have two S-ATA hard disks and a S-ATA optical drive (not a ludicrous setup by any means), you'll have to put more effort into tidying your cabling than you would with other boards.
More important is the layout of the expansion slots. If you plan to use 3-Way SLI (which is currently available only with dual-slot GeForce 8800 GTX and Ultra cards), then you won't be able to use the two PCI slots and single 1x PCI-E slot. Considering that anyone wanting £1,200-worth of dedicated graphics hardware might also want an X-Fi and a Killer NIC, the fact that there are no free expansion slots after 3-Way SLI has been installed isn't ideal. Even one slot above the uppermost graphics slot would have been handy. Those with less cash should remember that they can use one of the 16x PCI-E slots for any type of PCI-E card.
As you'd expect from a premium motherboard, the back panel is crammed with ports, from dual LAN ports to an optical S/PDIF output. Unlike some premium Asus motherboards, there are also two PS/2 ports for non-USB mice and keyboards, and an additional four-USB-port backplate for a total of ten ports. However, there's no integrated WiFi.
Performance
With the chipset's sweltering heat giving an impression of lots of raw power, we were prepared for some awesome speeds from our Media Benchmarks. Sadly, they never materialised; out of the box, the XFX can even be described as a little sluggish.
The image-editing and video-encoding tests returned lacklustre scores of 961 and 992 respectively, which would have placed the board near the bottom of the pack in the motherboard Labs. The multitasking score is the worst of the lot, with a puny 719 points dragging down the overall score to a disappointing 891.
At least overclocking was a pleasant and straightforward process, with the unlinked memory proving especially handy. We locked our standard Corsair test RAM at its usual frequency and went to work on finding the maximum FSB. It topped out at 510MHz, so there's clearly potential for overclocking.
With the CPU voltage set to 1.525V and the annoying Northbridge fan in place, our CPU was perfectly stable at 3.66GHz with an FSB of 458MHz (1,832MHz effective). Again, however, the system's performance in our tests wasn't as good as we hoped. Image editing returned a modest score of 1,286, which is 77 points off the record set by the P35-based Asus P5K Premium WiFi-AP. The XFX didn't set the world alight at video encoding either, scoring 1,298. We'd expect around 1,360 from a good overclocking motherboard.
Conclusion
Two of the 780i SLI chipset's selling points are its native support for Intel's 1,600MHz FSB CPUs and 3-Way SLI. With 3-Way SLI making about as much financial sense as a Fabergé Egg-and-spoon race, it isn't at the top of our list of priorities. You also don't technically need official support for a 1,600MHz FSB to run 1,600MHz FSB CPUs. Older motherboards, such as the Asus P5B Deluxe, will run them fine after a BIOS re-flash. Considering its price of £173, the XFX nForce 780i SLI offers little to justify the extra cost over a standard P35 board. Unless you absolutely must go beyond 80fps in Call of Duty 4 on your 24in TFT using 3-Way SLI, there's little to recommend this motherboard.
