The MSI P7N SLI motherboard uses the new Nvidia nForce 750i SLI chipset so let's get straight to the silicon at the heart of the matter.
Although we had a few issues with the nForce 600 family of chipsets due to their price and colossal heat output you knew exactly what you were getting in each case. The 680i SLI supports three graphics slots, the 650i SLI supports regular SLI and the 630i does none of the above as it has a single graphics slot.
Love ‘em or loath ‘em the 680i SLI and 650i SLI chipsets have been your only options if you want to run dual Nvidia graphics cards in SLI with a Core 2 processor. As a bonus Nvidia recently added Tri-SLI driver support for the 680i SLI which might appeal to the handful of rich gamers who can afford three 8800GTX or Ultra graphics cards.
The 600 chips are due for an update so enter stage left the nForce 700 chipsets. It's hard to think of these chipsets as a family as there are only two members. The 780i SLI replaces the 680i SLI while the 750i SLI takes over from the 650i SLI. There's no mainstream chip as Nvidia cannot compete with the superb Intel P35 chipset.
Both the 750i SLI and 780i SLI add support for Intel's 45nm Penryn processor along with a degree of PCI Express 2.0 graphics support but that's not exactly the same thing as a move from PCI Express 1.1 to 2.0. The 780i SLI is little more than a 680i SLI with an add-in nForce 200 chip that brings a mix of PCI Express 1.1 and 2.0 to the three graphics slots. The nForce 750i SLI also uses the nForce 200 chip but there's no messing around with PCI Express 1.1.
You can tell that from the photo of the MSI P7N SLI by reciting the mantra ‘If it's blue it's 2' as all three PCI-Express slots on the MSI are blue in colour. The main slot is dark blue and delivers 16 lanes of PCI Express 2.0 while the other two slots are light blue and supply eight lanes. If you use SLI the main slot drops in bandwidth so each graphics card gets eights lanes of PCI Express but because it's Gen 2.0 you won't suffer a bottleneck in performance. According to Nvidia you can't use the three slots in Tri-SLI as that privilege is reserved for the 680i SLI and 780i SLI so the third PCI Express slot will be for other duties such as a TV tuner, RAID card or audio card.