As the name suggests the MSI P45 Platinum is based on the new Intel P45 chipset. This is an evolution of the superb P35 and you need to take a close look to spot the differences between the two pieces of silicon.
P35 has a total of 20 lanes of PCI Express Gen 1 with 16 lanes for the main graphics card. Add a second ATi card in CrossFire and it gets a mere four lanes of PCI Express, while adding insult to injury any PCI Express expansion slots on the board are disabled.
In essence, then, P35 is only intended to offer support for a single graphics card, but with P45 the graphics support is far more sensible. You still get 20 lanes of PCI Express but it is Gen 2, with double the bandwidth that operates with 16 lanes for a single graphics card or dual x8 if you're using CrossFire. There are a number of vendors offering X2 graphics cards with two Radeon GPUs on a single graphics card, so it is perfectly possible to install four GPUs in two graphics slots to achieve CrossFire X on the P45 chipset.
This is a useful change, but it's under the surface with the result that the P45 Platinum looks very similar to the P35 Platinum. Indeed, the only discernable visual difference on the P45 Platinum is the Circu-Pipe 2 cooling system, which has been heavily revised from the original Circu-Pipe that we saw on the X38 Diamond and X48 Platinum models.
This new system adds a small vertical cooler to the end of each of the five heatpipes that are used to conduct heat from the chipset and power regulation hardware. These five coolers are arranged like the cylinders of an old aircraft engine on top of the Northbridge heatsink, where they look neat and provide plenty of space for the CPU cooler.
Processor support with the new P45 is unchanged from P35. Its maximum official front side bus of 1,333MHz rules out the Core 2 Extreme QX9770, however MSI claims that its range of P45 boards will overclock to 2,008MHz. That's an unusual quad-pumped figure of 502MHz, which is a big step up from 333MHz and should give overclockers plenty of scope.