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ASRock X99 Extreme6/ac Motherboard Review

Featuring the same wireless controller as its closest competitor, ASRock’s X99 Pro adds a second gigabit Ethernet controller and removes a few pathway sharing issues. Have we finally found a value-winning solution for high-end LGA 2011-v3 buyers?

ASRock’s X99 Extreme6/ac In Detail

A PCIe 3.0 configuration that drops from x16-x16-x8 to x16-x8-x4 when using a 28-lane CPU might not be a big deal to most builders, since so few use three-way SLI anyway. And a configuration that drops the third slot entirely might not be a deal-killer to PCIe-based M.2 SSD users, since so few of them need a third x16-length slot. It’s not as though an enthusiast would automatically lose that slot with any M.2 SSD. After all, ASRock does provide it a single SATA 6Gb/s connection as an alternative. Instead, we’re probably only looking at power users attempting to build the ultimate mid-price gaming machine as this board's missed target.

A comparison of ASRock's X99 Extreme6/ac to Asus' X99 Pro is inevitable, since both boards use the same PCIe 3.0 slot configuration and add-in USB 3.0 controllers. ASRock connects all four ports of its USB 3.0 hub to a single 5Gb/s chipset port, along with the two ports of the additional PCIe-based controller to a single 5Gb/s lane. ASRock goes on to add a second gigabit Ethernet controller and a single eSATA port compared to its competitor, relocating the Wi-Fi antenna connectors to the I/O shield in the process.

Dissimilarities between the Qualcomm Atheros network controller and Intel-based network PHY prevent teaming.

ASRock doesn’t feature its competitor’s custom firmware flashing ASIC, but does add a feature that many enthusiast appreciate in its dual, manually-selectable firmware ROMs. Both can even be removed and replaced, just in case you suffer an extremely unfortunate combination of bad luck and poor judgment.

Lacking its competitor’s four-lane PCIe 2.0 x16 connector, ASRock's customers can’t suffer the loss of the wireless controller by setting that slot to x4 mode. The same goes for the I/O panel-based USB 3.0. ASRock instead puts a PCIe x1 slot in the same place, refusing to overcommit the chipset’s eight-lane PCIe 2.0 controller. Sometimes, the simplest solutions are best.

As with Asus' board, four of the X99 Extreme6/ac’s six X99-based USB 3.0 ports are connected to front-panel headers. Unlike the competition, ASRock places both headers above the X99 Extreme6/ac’s top expansion slot to prevent any possible installation conflicts.

The X99 Extreme6/ac doesn’t offer Asus' SATA-Express connector, instead relying exclusively on Ultra M.2 (in PCIe x4 mode) or, for those who aren’t willing to disable the third PCIe 3.0 slot, traditional SATA RAID. Similarly, its competitor’s array of dual-control (voltage and PWM) four-pin fan connectors is reduced on the X99 Extreme6/ac to two four-pin and four three-pin headers.

Unique to ASRock is the HDD Saver connector, which can enable or disable power to two hard drives on demand. Password-securable, users can turn off the drive to save power and wear, and to prevent access by “friendly” guests, even while keeping their Windows user logged in. I’ve read that the technology can be used to prevent seldom-used mechanical drives from locking up (by occasionally power-cycling them), though I’ve never personally had an unused drive seize in storage.

One ever-present layout concern is the front-panel audio header shoved all the way into the X99 Extreme6/ac’s bottom-rear corner. Typically opposite of the port’s placement on a case, we still find that the cables of some cases are slightly too short to reach that corner. ASRock’s competitor beats the X99 Extreme6/ac on this, since the X99 Pro’s connector was moved forward by more than an inch.

The X99 Extreme6/ac installation kit includes two- and three-way SLI bridges, four SATA cables, a two-drive SATA power cable for the HDD Saver header, antenna leads for the I/O panel and a Wi-Fi antenna.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.