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Asus' P9X79 PRO motherboard
Asus has been on a bit of a tear lately. The company's first Sandy Bridge motherboards were easily the most attractive examples of the breed thanks to intelligent features and the best firmware in the business. With a $329 expected price tag, the P9X79 PRO will have to deliver on both fronts; this is the second most expensive board of the bunch.

At first glance, the PRO certainly looks the part of a high-end motherboard. There's a lot going on, including no fewer than four separate heatsinks to cover the chipset and power regulation circuitry. Heatpipes link the coolers in pairs, and the mass of finned, anodized metal looks rather attractive. The mix of black, white, and different shades of blue is at least a small deviation from the black-and-blue uniform worn by most enthusiast-oriented motherboards lately.

Asus has used digital power delivery circuitry for the CPU through multiple generations of motherboards. With its X79 family, digital VRMs have also been applied to the memory. The digital circuitry is purportedly more accurate and responsive than analog alternatives, which Asus claims improves overall stability. A total of eight power phases is dedicated to the CPU core, while another two feed the rest of the chip. An additional four power phases are split between the system's two banks of DIMM slots.

The memory slots are only 20 mm from the edge of the CPU socket, so you'll want to be careful about combining big aftermarket heatsinks with tall DIMMs. Two of the VRM heatsinks also crowd the socket, although they're not much more than an inch tall. After swapping a Core i7-3960X back and forth between motherboards for a week, I've gotta say I dig the new socket's screw-in retention bracket.

Asus has gone all-PCIe with the PRO's expansion slot layout, which includes a pair of x1 slots in addition to a quartet of x16s. The blue x16 slots have 16 lanes of PCIe 3.0 bandwidth each, and the bottom one shares lanes with the top white x16 slot in an x16/x8/x8 config. The second white slot has eight lanes of dedicated PCI Express 3.0 connectivity. As you can see, the slots are arranged such that dual-double-wide graphics configurations won't block access to the white x16s, which enjoy a direct path to the CPU.

To the right of the expansion slots sits a cluster of edge-facing SATA ports. The white ones offer 6Gbps connectivity, while the blue ones are capped at 3Gbps. The 6Gbps ports with the little red sticker are tied to a Marvell controller and are a part of Asus' new SSD caching scheme. Marvell has a HyperDuo caching system of its own, but Asus has whipped up custom software and algorithms for its own implementation. Asus' approach works like Intel's Smart Response Technology, allowing an SSD to cache both reads and writes associated with a mechanical hard drive attached to the same controller.

The port cluster provides plenty of goodies, including a Bluetooth transceiver and a BIOS Flashback button. The Flashback functionality allows the board's firmware to be updated using only a thumb drive and a power supply—no CPU or memory required. This handy little feature should ensure older boards can easily be updated to support new CPUs.

With the exception of the missing FireWire port, the rest of the cluster is pretty standard fare. Kudos to Asus for equipping the eSATA ports, which are tied to an ASMedia 6Gbps controller, with USB power. Two more ASMedia controllers handle the USB 3.0 ports with a little help from a four-port Via hub chip. One of the controllers is tasked with supplying the front-panel ports, while the second combines with the Via chip to feed the four ports in the rear cluster. The hub chip has only one upstream port, so it's possible that one of the rear ports is connected directly to the ASMedia controller, and thus not sharing bandwidth with the others. We're still waiting for Asus to confirm whether that's the case.

The PRO's SuperSpeed ports are enhanced by a feature called USB Boost, which uses a USB Attached SCSI Protocol (USAP) that's supposed to deliver faster transfer rates when paired with USAP-compatible devices. USAP-compatible devices appear to be rather rare, but there's also a Turbo mode designed to work with USB 3.0 gear that relies on the old Bulk-Only Transport protocol that's been around since version 1.1 of the standard. In the short amount of time we've been able to devote to USB Boost, we've encountered compatibility problems with at least one solid-state drive—in both an older USB 3.0 docking station and a USAP-aware enclosure that Asus sent over. Asus is looking into the matter, and we may have to spend more time with USB Boost once the kinks are ironed out.

Although Realtek networking chips have been banished from the X79 boards we've collected today, the company's new ALC898 codec appears on the P9X79 PRO. Asus augments the chip with DTS software that offers surround-sound virtualization. Another DTS component encodes surround-sound bitstreams in real time, enabling multi-channel game audio to be piped to compatible receivers and speakers over a digital output that bypasses the onboard DAC. This is as robust an integrated audio solution as we've seen.

Asus' UEFI is the standard by which all others are judged, not only for its visual flair, but also for the responsiveness of its interface and the wealth of options that lie within. The P9X79 PRO doesn't bring big changes, but Asus has made a few tweaks that are worth noting. One recent addition is the ability to take screenshots, which are saved to an attached thumb drive and make the GUI look much nicer when shown off in reviews like this one. Asus has also added a new shortcut menu that's invoked with the F3 key and provides quick access to commonly used options like fan controls, DRAM timings, and CPU performance settings.

The interface is as snappy as ever, and the overclocking and tweaking options are generally excellent. However, the firmware takes liberties with Turbo multipliers that it really shouldn't. If you set the memory clock manually, Asus replaces CPU's default Turbo behavior, which is to use a mix of 39, 37, and 36X multipliers depending on the number of active cores, with a blanket 39X multiplier for all loads. There's no message to the user indicating that this change has taken place, and none of the other X79 boards we've tested mess with CPU multipliers in the same way. Simply put, this behavior is unacceptable. Changing one system setting shouldn't secretly alter another, especially when they're unrelated. Thankfully, it's possible to define the correct Turbo behavior manually through the firmware.

Asus doesn't mess around with the fan options, which offer temperature-based speed control for all the onboard headers. Users can set temperature limits and duty cycles in 1°C and 1% increments, respectively, and there's even more fan control goodness available in Windows.

Rather than restricting users to minimum and maximum values, Asus' FanXpert+ software provides control over a third point on each fan profile. The drag-and-drop interface makes tweaking fan profiles a joy, and as in the firmware, it's possible to define different behavior for each onboard fan header. These fan controls are designed for four-pin PWM fans, but they'll also work with three-pin DC models plugged into the CPU and first chassis headers.

FanXpert+ is neatly integrated into the AI Suite Windows utility, which also has built-in overclocking controls. Using AI Suite's TurboV EVO application, it's possible to change clock speeds, multipliers, and voltages. A separate AI Suite component provides control over the board's power delivery circuitry for the CPU and memory. Stay tuned for a closer look at that auto-tuning button in the overclocking section of the round-up.