Connectivity: USB and Thunderbolt
Most Z170 motherboards tested by us have USB 3.1 ports, which are almost always controlled by a ASMedia ASM1142 controller. Some boards from Gigabyte are an exception to this rule, since they are equipped with the Intel Alpine Ridge. This controller is faster in principle than the ASM1142, but we haven't succeeded in successfully completing a test with our test system. At the end of this year the controller will be officially released and considering Intel's track record we can't imagine any possible problems persisting very long after release.
ASRock does USB the best with their Extreme6. All USB ports on the I/O panel have a minimum speed equal to USB 3.0. The Gigabyte Z170X-Gaming 5 offers the most USB ports on the I/O panel, in this case nine. The Maximus VIII Ranger on the other hand offers noticeably so less fast USB ports on the I/O panel. It only has two USB 3.0 ports, but it does offer headers for 4 times USB 3.0. This isn't very useful since there are only two USB 3.0 ports on most cases. Only exceptional and super expensive models offer four.
|Motherboard||USB 3.1 external||USB 3.1 front panel||USB 3.0 external||USB 3.0 internal||USB 2.0 external||USB 2.0 internal||Thunderbolt 3|
|ASRock Z170 Extreme6||1 A + 1 C (ASMedia ASM1142)||-||6 A||2||0||4||-|
|ASUS Maximus VIII Ranger||1 A + 1 C (ASMedia ASM1142)||-||2 A||4||4||4||-|
|Gigabyte Z170X-Gaming 5||1 A + 1 C (Intel Alpine Ridge)||-||3 A||4||4||4||-|
|MSI Z170A Gaming M5||1 A + 1 C (ASMedia ASM1142)||-||4 A||2||2||4||-|