The Intel Z370-chipset
As the 'new' socket 1151 is unofficially called 'socket 1151 v2', we could also call the Z370-chipset 'Z270 v2'. Sources in the industry tell us that the Z370-chipset is identical to Z270, with the only difference being that it is suited for the new CPUs. We already tested this and could not get Coffee Lake to work on Z270 while also being unable to get Kaby Lake to work on Z370. In any case, like Z270, Z370 offers a total of thirty I/O-lanes that manufacturers can in part utilize at their own discretion for (for example) SATA- and USB-connectors.
Of those thirty lanes a maximum of ten can be used for USB 3.0, a maximum of six for SATA600 and a maximum of 24 for PCI-Express 3.0. This offers manufacturers the flexibility to vary with features and thereby creating motherboards for different target audiences. There will always remain more than enough lanes for two or even more M.2-SSDs that can operate at full speed. The maximum speed between the CPU and the chipset via the DMI 3.0-interface is set to slightly below 4 GB/s, meaning that devices connected only via the chipset will be unable to together achieve higher speeds than that.
With the introduction of Z270 we already complained about the absence of new technologies such as USB 3.1 and Thunderbolt, but with Z370 support for these is still missing. Despite the fact that Intel themselves are one of the main driving forces behind both standards, they are quite far behind AMD, as this company has already built USB 3.1 into their own Ryzen-chipsets.
The 'real' 300-series chipsets...
The first rumors about the new series chipsets spoke of a ton of new features: USB 3.1 of course, but also built-in WiFi and even Thunderbolt-integration. None of this is found in Z370. In fact, we wrote before that the hardware of the new chipset is presumably identical to Z270. How did that happen?
What was originally planned as 300-series chipsets is simply not what has been released now. Intel chose to expedite the introduction of the 6-core Coffee Lake-CPUs - the competition of AMD will undoubtedly have had something to do with this. A direct result of this is that the chipsets are not yet finished; therefore Intel chose a rebrand of Z270 as an in-between solution.
In the first quarter of 2018 we will see the introduction of a lot more Coffee Lake-processors, among which more quadcores and dualcores, as well as the H310-, H370- and B360-chipsets. That last chipset is the successor to B250, but considering the fact that B350 has already been claimed by AMD, Intel was forced to change their naming. We assume that these chipsets do offer new features. In the summer of next year there is even a Z390-chipset planned that will bring the same functionality to the high-end chipset as well.