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Asus' Z170-A motherboard reviewed

Our first look at the new breed
— 10:46 AM on August 5, 2015

Skylake has arrived, and along with the processors themselves come Intel's 100-series chipsets. The Z170 platform caters to PC enthusiasts, and it brings some notable upgrades over the last-generation Z97 enthusiast chipset.

First off, Z170 is a major USB upgrade. Fourteen USB ports sprout from the Z170 platform. That's the same number as with the Z97, but now, up to ten of them can be USB 3.0. The "up to" qualifier exists because details like these are dependent on how the motherboard maker decides to use the chipset's flexible I/O lanes. Are consumers given the maximum number of PCIe lanes for expansion cards, or does the pendulum swing toward maximizing USB 3.0 ports? Point is: mobo makers have options.

Z170's PCI Express connectivity has also been upgraded to Gen3 speeds. Not only does this upgrade double the bandwidth for lanes coming from the chipset, but it also doubles the bandwidth for the DMI link between the processor and the chipset. This latter point is important as PCIe SSDs become more prevalent. Auxiliary controllers like USB 3.1 chips also get access to more bandwidth. The fatter DMI pipe lets the processor shuffle bits more rapidly to the increasingly bandwidth-hungry I/O devices hanging off the chipset.

The Z170 platform also gives us some expected-but-welcome enthusiast-friendly features, like the ability to split the processor's sixteen Gen3 PCIe lanes for multi-GPU graphics configs. The Z170 also offers full control over Skylake's various knobs and dials, allowing overclockers to tweak to their hearts' content.

The first Z170 board that we've put through its paces is Asus' Z170-A.

With the 100-series boards, Asus has brought over some of the familiar black-and-white aesthetic that we saw on their X99-based boards, but it's made a few tweaks. Instead of heatsinks clad in matte black, Asus has gone with silver. Unlike the Z170-A's X99 brethren, the board itself isn't completely black, either.

A more blacked-out look can be had by removing the large plastic cover that shrouds the rear port cluster and the left VRM heatsink. This cover is purely cosmetic, and it's secured with just three screws on the underside of the board. Removing it could also improve airflow to that left VRM heatsink.

Skylake eschews the fully-integrated voltage regulator (FIVR) used by Haswell chips, so it falls to the motherboard's VRMs to supply each of the input voltage rails the processor requires. To accomplish this task, Asus uses eight digitally controlled phases for the CPU and two for Skylake's integrated GPU. Both VRM heatsinks are held in place with push-pins rather than screws.

One of Skylake's key features is support for DDR4 memory. The Z170-A's four DIMM slots only accept 288-pin DDR4 DIMMs—older 240-pin DDR3 sticks need not apply. Asus recommends installing DIMMs in the gray slots first. If you're only installing two sticks, that gives maximum clearance between the processor's heatsink or water block and the DIMMs. Thanks to DDR4's higher-density modules, up to 64GB of RAM can be installed with all four slots populated. Asus uses slots with locking mechanisms on only one end, which can make life easier when swapping DIMMs in crowded cases.

Thankfully, Skylake's LGA1151 socket maintains compatibility with existing LGA1150 heatsink and water block mounting mechanisms. As always, if you're using an oversized CPU cooler, be sure to check for adequate DIMM clearance first. Here are some measurements to help you figure out which components can safely fit together on the board:

The CPU socket has a lot of breathing room thanks to a healthy distance not only to the VRM heatsinks, but also the first PCIe x16 slot. In close proximity to the CPU socket are a total of six fan headers, including a special one meant exclusively for all-in-one liquid coolers' pumps.

The Z170-A serves up three x16 PCIe slots. When one graphics card is installed, all sixteen of Skylake's Gen3 PCIe lanes are routed to the gray slot at the left. Those wanting to partake in some dual-GPU fun should use the left and middle x16 slots: with two cards installed, each will get eight Gen3 PCIe lanes from the CPU. The third x16 slot, rightmost in the picture above, is fed with either four or two Gen3 lanes. When that slot is configured to operate as an x4 slot in the firmware, two of the board's SATA 6Gbps ports are disabled, since they both share the same flexible I/O lanes from the chipset.

This arrangement grants support for two-way SLI setups and, thanks to more lenient bandwidth requirements, room for up to three-way CrossFire configs. That said, we usually recommend going for the fastest single graphics card you can afford before stepping up to more exotic multi-GPU setups.

Peppered around those three x16 PCIe slots, we find three x1 slots fed by Gen3 lanes from the chipset, as well as an old-school PCI slot driven by an ASMedia PCIe-to-PCI bridge chip.

That's a lot of words. Here's a graphical representation of the Z170-A's expansion slots and how each one is connected.

The expansion slots can handle something as wild as a pair of triple-slot video cards, but in more typical multi-GPU setups, a pair of double-slot cards won't obscure the leftmost x1 slot, the middle PCI slot, or the rightmost PCIe x16 slot.

Now, on to the Z170-A's storage subsystem.