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Intel's P55 Express chipset


A look at Asus' P7P55D Deluxe, Gigabyte's GA-P55-UD6, and MSI's P55-GD65
— 12:29 AM on September 8, 2009

For years, Intel's core-logic chipsets have set the standard against which all others are judged—as long as we're not talking about integrated graphics performance, anyway. You'd have to dig all the way back into the pre-Prescott era for an Intel chipset with serious issues. Finding flaw with relatively recent core-logic offerings from AMD and Nvidia is considerably easier, however. During Intel's reign, AMD's south bridge chips have struggled with all sorts of issues, from slow USB and PCI performance to generally flakey AHCI implementations. Nvidia's nForce designs have had their share of problems, too, like bouts with data corruption and generally higher power consumption.

A relative lack of quirky issues has made Intel chipsets particularly popular among enthusiasts. The mid-range models have been the most iconic, not just because they've offered all the performance and stability of higher-end variants, but because they've generally taken well to overclocking. Such was the case with the P45 Express we've been enjoying for more than a year now, the P35 that came before it, the P965 before that, and so on.

Today, Intel's latest mid-range chipset makes its debut alongside Lynnfield-based Core i5 and i7 processors. Ladies and gentlemen, I present you the P55 Express.


Yep, that's it: one chip. It's not really a chipset, is it? Intel calls this slice of silicon the P55 Express Platform Controller Hub, or PCH. The chip is fabbed using 65-nano process technology, and it's tiny. According to my ruler, the PCH measures just 8.5 x 9 mm for a total die area of around 76.5 mm².

Intel can get away with such a small, single chip because Lynnfield moves much of the chipset's traditional duties onto the CPU. Like its Bloomfield-based Core i7 predecessors, Lynnfield CPUs have integrated memory controllers. You're limited to two DDR3 memory channels, but speeds are supported up to an effective 1333MHz. This latest Nehalem iteration also brings a sweet 16 lanes of second-generation PCI Express connectivity onto the processor package, consolidating CPU and north bridge components under one roof.

Lynnfield's PCI Express lanes can be configured as a single x16 link or split between a pair of x8s for multi-GPU configurations. CrossFire support is universal, but as with Intel's X58 chipset, SLI certification is handled at the motherboard level. All boards should be able to combine a single GeForce graphics card with a second one for dedicated PhysX acceleration, provided they have a second physical x16 slot. You can also add a dedicated PhysX card to an SLI-certified board running a pair of GeForces in tandem. If that wasn't excessive enough, some uber-high-end P55 boards will also feature nForce 200 chips and support for three-way SLI. Such extravagance seems silly given the P55's mid-range aspirations, but that's how mobo makers roll these days.

Lynnfield has enough PCI Express lanes for most graphics configs. What about expansion slots and peripherals, though? That's where the P55 Express PCH comes in. It's equipped with eight gen-two PCIe lanes—two more than the old ICH10R south bridge. However, these lanes only offer signaling rates up to 2.5GT/s, which is the same speed as gen-one PCI Express. That's unlikely to be a major impediment in mid-range systems, but it will limit the bandwidth available to high-end RAID cards, and the like.


Little has changed in the Serial ATA department, however. The P55's six-channel SATA controller is largely the same as the one in the ICH10R, so it's loaded with RAID functionality but lacking support for next-gen 6Gbps transfer rates. Intel says it's looking at the new standard, but that only SSDs are likely to benefit from greater interface bandwidth. Not even today's fastest SSDs can saturate a 3Gbps SATA link, anyway.

On the networking front, the P55 has a Gigabit Ethernet MAC that will consume one of the board's PCI Express lanes if tapped. So much for saving an expansion slot with integrated GigE. Intel has made some changes in the P55's USB component, as well, retaining the dual-controller design while adding two ports for a total of 14. Throw in an HD audio interface, and that just about does it for the P55.

The PCH is linked to the CPU via a 2GB/s DMI interconnect similar to the one Intel used to join the north and south bridge components of its last several chipsets. I suppose that makes sense given that this is still an I/O hub link, but the pipe doesn't look nearly fat enough on paper. The DMI connection's 2GB/s of peak bandwidth is equivalent to just four of the PCH's half-bandwidth PCIe 2.0 lanes. And the P55 PCH has another four of those, plus SATA, USB, and other lesser chipset functions to clog things up. The average mid-range PC is only likely to have a few hard drives and USB peripherals, though, and it probably won't be maxing too many of those PCIe lanes at once.

I have to admire the elegant simplicity of the P55 PCH, but there isn't much to the actual chip. The same can't be said about the first wave of P55-based motherboards to hit the Benchmarking Sweatshop. What the PCH lacks in flash, it makes up for by packing a heck of a lot of connectivity into a very small package, allowing motherboard makers to load up on expansion slots and peripherals to complement their ever-evolving arsenals of overclocking options and useful new features.

That ordnance is on full display in the first wave of P55 boards from the big three: Asus' P7P55D Deluxe, Gigabyte's GA-P55-UD6, and MSI's P55-GD65. Rather conveniently, we've arranged an in-depth throwdown to see how they compare. We'll dive into the results of our exhaustive suite of chipset and motherboard tests in a moment, but first, let's properly introduce these Lynnfield-ready mobos.