ASRock Z97 Extreme6
BIOS/UEFI:
ASRock provides a very nice UEFI interface for the Z97 Extreme6 motherboard. Offered from the ASRock UEFI are a plethora of options for tweaking the system and pushing it to its maximum performance for those interested in overclocking. ASRock Instant Flash is also available for easily upgrading the BIOS without having to resort to any Windows or DOS programs, plus the dual/back-up BIOS feature of this motherboard is very nice, especially if this motherboard is supported someday by Coreboot.
Linux Compatibility:
With all of the Intel Z97 Express motherboards I have tested to date I have not run into any major compatibility troubles when running modern Linux distributions. The only real issue encountered with the modern motherboards have been the lack of LM_Sensors support for being able to detect and read the onboard motherboard hardware sensors (temperatures, fan speeds, voltages, etc). The ASRock Z97 Exteme6 is no different to the other Z97 motherboards tested at Phoronix. The ASRock Z97 Extreme6 happily booted up on Ubuntu 14.04 LTS without any issues, but was unable to detect any onboard sensors besides for the coretemp driver reading the Core i7 processor's thermal data. With time, LM_Sensors should support this motherboard but for most Linux users out there this is of no concern. Even with the Z97 Extreme6 being packed with features, it was working fine. The only major functionality that I wasn't able to test was the M.2 SSD connectors for lack of hardware and the Thunderbolt AIC connection, but all key functionality of this Z97 motherboard was working fine in my tests. For best support, especially if using Intel HD Graphics, the newer the Linux kernel generally results in the better and most performant experience.
Linux Performance:
For some initial Linux benchmarks from the ASRock Z97 Extreme6 motherboard, its performance was compared to a Gigabyte Z97-HD3 and ECS Z87H3-A2X EXTREME motherboards that were readily on-hand. The Linux benchmarking was handled by the Phoronix Test Suite. All tests were done with an Intel Core i7 4770K CPU, 16GB of DDR3-1600MHz system memory, 120GB Samsung 840 Series SSD, and using the integrated HD Graphics 4600. Ubuntu 14.04 was running on all three setups with a Git snapshot of the Linux 3.15 kernel and using Mesa 10.3-devel.