More expensive boards, but cooler CPUs
lanes. In addition, this would allow motherboard manufacturers to implement up to three PCIe 3.0 x4 M.2 slots on their boards, complete with RAID support. But even though Z170 officially supports 10 USB 3.0 ports (up from six on Z97), six SATA 6Gbps ports, and 20 PCIe 3.0 lanes, you can’t have everything all at once because the USB 3.0 and SATA ports use PCIe lanes as well. For example, populating both M.2 PCIe 3.0 x4 slots on the MSI Z170A Gaming M9 ACK will end up disabling two of the six SATA 6Gbps ports. This is because the SATA ports use a PCIe lane each, which overlaps with the lanes used for the M.2 slots. Finally, Intel Z170 will see motherboard manufacturers return to implementing voltage regulation on the board itself. This was the case prior to Haswell CPUs, but Z97 and Haswell/Broadwell processors saw Intel create a fully integrated voltage regulator (FIVR) on the CPU itself in order to reduce motherboard costs and power consumption. However, this also had a less desirable consequence in the form of additional heat output in overclocked CPUs. As a result, overclocking was limited by temperatures, and also by the varying quality of the FIVR on individual chips.
With Skylake and Z170, Intel has handed the task of voltage regulation back to motherboard, which could result in cooler processors, but slightly more pricey boards.
The top two PCIe 3.0 x16 slots feature metal reinforcements to support heavier graphics cards.