Consistency is a hard thing to come by in this industry, but year after year, Intel has managed to deliver excellent mid-range core logic chipsets. Since its launch last spring, the P35 Express has been the best bang-for-your-buck Core 2 chipset on the market—a position inherited from its P965 predecessor, which was the LGA775 platform of choice in its day. The P965's crown, of course, was a hand-me-down from the Intel 915P chipset that came before it, which in turn, well, you get the picture.

Intel's mid-range chipsets are perhaps the very definition of the sweet spot; they offer nearly all the performance of the company's high-end chipsets and comparable features at a fraction of the cost. Trickle-down is a wonderful thing indeed, and its value hasn't been lost on motherboard makers, which tend to eagerly snap up Intel's latest mid-range chipsets and deploy them across a wide range of different products. We've seen the latest P35 Express featured in stripped-down budget boards selling for less than $100, enthusiast-oriented offerings draped in indulgent excess that cost $200 and up, and all points in between.

Given the impressive flexibility and consistent quality of Intel's mid-range chipsets, we've naturally been looking forward to the new P45 Express with bated breath. This successor to the P35 hasn't yet been formally announced, but we managed to get our hands on P45-based P5Q and P5Q3 Deluxe motherboards from Asus to run through the wringer. Read on to see if Intel's latest mid-range chipset lives up to its lineage.

P45 under the hood
While some motherboard makers garishly adorn their enthusiast boards with neon, glow-in-the-dark, or otherwise look-at-me trim, Asus manages to keep the P5Q and P5Q3 Deluxe looking classy. The boards still have a little flash thanks to polished copper heatsinks and blue accents, but it's the kind of restrained bling that shouldn't offend anyone. Looks don't matter, of course, unless you're going to be admiring your system through a case window—something that a PC enthusiast particularly proud of their rig might be inclined to do from time to time. Not that I'd ever admit to such a thing.

The star of the P5Q line is Intel's new P45 Express chipset, which in a bit of a surprise, only offers official support for front-side bus speeds up to 1333MHz. We'd expected the P45 to natively support 1600MHz front-side bus speeds like Intel's high-end X48 chipset, but that doesn't appear to be the case. Official limitations haven't stopped Asus from making faster front-side bus speeds available in the BIOS, though. More on those in a moment.

Like the P35 Express that preceded it, the P45's memory controller supports either DDR2 or DDR3 memory. Asus' P5Q Deluxe is built for the former with the P5Q3 Deluxe equipped for the latter. Apart from their memory slots, the boards are identical. We don't expect there to be much interest in the P5Q3 given current memory prices, though; DDR3 is still far too expensive in relation to DDR2 to justify its marginal performance and power consumption advantages.

At least both boards share the same layout, which is generally excellent. Primary and auxiliary power plugs are located right along the edges of the board where we like to see them, reducing airflow-constricting cable clutter around the CPU socket. This power plug placement can be problematic for upside-down cases or extremely small mid-towers that have little clearance between the motherboard and PSU, but it's the best compromise for the majority of systems. An auxiliary 12V power plug extender can easily remedy compatibility issues with upside-down cases, anyway.

Asus unsurprisingly rings the CPU socket on its P5Qs with a collection of heatpipe-linked passive heatsinks. This chipset and voltage circuitry cooling uses relatively low-profile cooling fins, leaving enough clearance for larger aftermarket processor heatsinks like Scythe's enormous Ninja. An auxiliary cooling fan that clips onto the chipset cooler is also provided for systems with limited ambient airflow.

We didn't need the fan on our open test bench or through most of our overclocking testing, suggesting that the P45 runs very cool indeed. The P45 Express chipset is fabbed using a 65nm process node that should yield lower power consumption—and therefore less heat output—than previous Intel chipsets based on 90nm fabrication technology.

To further reduce power consumption, the P5Qs also feature what Asus calls an Energy Processing Unit that fine-tunes the power supplied to the processor and other system components at lower load levels. The EPU is capable of scaling CPU power phases, too, throttling the board's 16 power phases down to just eight or four depending on system load.

The P45 Express chipset features a new ICH10R south bridge, which as far as we can tell, is little more than a die-shrunk ICH9R. No new hotness here, just the same six 300MB/s Serial ATA RAID ports you got on the ICH9R. Five of those ports are smartly placed out of the way of longer graphics cards, but the sixth can be a bit problematic.

Since the ICH10R doesn't resurrect "parallel" ATA support, Asus has to opt for an auxiliary storage controller from Marvell to provide an IDE port. The Marvell chip also snakes a little eSATA love to the port cluster, but it isn't the only extra storage chip onboard. Asus also throws in some Silicon Image, er, silicon that has two SATA ports of its own that can be combined in RAID 0 and 1 arrays, or a combination of the two similar to Intel's Matrix RAID. What makes this RAID implementation particularly interesting is that the Silicon Image chip performs all array calculations in hardware and doesn't require any drivers. Arrays present themselves to the operating system as standard ATA devices that are, interestingly enough, connected to the Marvell chip's second Serial ATA.

PCI Express 2.0 finally hits Intel's mainstream chipsets in the P45 Express, whose north bridge contains 16 lanes of gen-two connectivity. On the P5Qs, these lanes can be split evenly between the first and second x16 slots or all dedicated to the first slot depending on how many graphics cards are installed. CrossFire is supported, of course, and there's even a third x16 slot hooked into the south bridge. The ICH10R's PCI Express implementation conforms to the older 1.1 standard, so there isn't quite as much bandwidth to go around. That third x16 slot only gets four lanes of bandwidth, and it has to share them with the board's two x1 slots. Onboard storage and networking controllers monopolize the remaining two south bridge PCIe lanes.

With an impressive seven expansion slots in total, the P5Qs even have room for a couple of old-school PCI slots. Squeezing in all those slots isn't an easy feat, though. Limited clearance between the memory modules and top PCI and PCIe x1 slots precludes the use of expansion cards longer than 74mm. You won't be able to run a double-wide CrossFire threesome, either.

High-end motherboards tend to provide a cornucopia of connectivity options, and the P5Qs are no exception. There's a little of everything here, including a single PS/2 port that can be used with either a mouse or a keyboard, but not both. That doesn't really help my PS/2 KVM switch, but it should appease users who may be unwilling to part with vintage buckling spring keyboards.

In the audio department, the port cluster is stacked with two flavors of digital S/PDIF output and a full complement of analog input and output ports, all fed by a new Analog Devices AD2000B codec chip. The AD2000B is an Asus exclusive, although it's unclear exactly how the chip differs from the older AD1988B. At the very least, it's disappointing that the AD2000B can't encode DTS or Dolby Digital Live bitstreams on the fly like some of Realtek's high-end audio codecs.

Dual Gigabit Ethernet options are common these days, and you'd think they'd be an easy feature to implement properly. Asus gets halfway there, too, tying one of the GigE ports to a PCI Express-based networking chip from Marvell. But the second GigE port is connected to a different Marvell chip that rides the slower (and shared) PCI bus, continuing an Asus tradition of fouling its high-end motherboards with at least one Gigabit chip that will be bottlenecked by the PCI bus. I suppose we can forgive Asus this time around because the P5Qs also come with integrated 802.11 Wi-Fi—a feature that will probably be more useful to most folks than a second GigE jack.

As is customary for high-end Asus motherboards, the P5Qs come with a few extra goodies. Buried under the usual mess of cables and manuals you'll find a pair of Wi-Fi antennas for use with the integrated 802.11n wireless controller and the auxiliary chipset cooling fan. Asus throws in a set of front panel connector blocks that really come in handy when putting systems together, too.

Speaking of little extras, we should also note that like many other high-end motherboards, the P5Qs are adorned exclusively with solid-state, conductive polymer capacitors. Contrary to some reports, Asus insists that these capacitors are all Japanese-made. You'll also find low RDS(on) MOSFETs and ferrite core chokes throughout, which Asus says makes the P5Qs more reliable overall and more stable when overclocked.