Page 3 : PCI Express, Ultra M.2, SATA Ports
PCI Express Slots
The ASRock Z170 Extreme4 motherboard has 6 PCI Express slots – 3 full-sized PCI Express 3.0 x16 slots, and 3 much smaller PCI Express 3.0 x1 slots. The top-most PCI Express 3.0 x16 slot (PCIE2) operates at full x16 speed with a single card.
If you have two graphics cards, you will need to install them in PCIE2 and PCIE4 and they will both run at x8 speed. If you install a third graphics cards in the PCIE6 slot, it will only run at x4 speed.
The three PCI Express 3.0 x1 slots are of the flexible design. That basically means an open-ended slot. This allows you to use any PCI Express card in those x1 slots, even x16 cards. The only downside is that they will only run at x1 speed.
Ultra M.2 Socket
The Ultra M.2 socket is a unique ASRock feature. The M.2 socket is usually connected to the Z170 chipset using two PCI Express lanes. ASRock has instead connected the M.2 socket directly to the Intel Core processor using four PCI Express lanes. This not only doubles the maximum bandwidth to 32 Gbits/s (4 GB/s), it also reduces the M.2 socket’s latency.
Of course, you will need an M.2 SSD that supports PCIe x4. Even so, PCIe x2 SSDs may benefit slightly from the lower latencies associated with the Ultra M.2 socket being directly connected to the CPU, bypassing the Z170 chipset.
The ASRock Z170 Extreme4 specifications officially quotes 3 SATA Express ports as well as 6 standard SATA 3 ports. However, that is not really the case – it only comes with 3 SATA Express ports.
Of course, each SATA Express port can be “converted” into 2 standard SATA 3 ports. After all, the SATA Express port is really just two SATA 3 ports with a smaller PCI Express port that delivers two PCIe lanes. So you can attach up to 3 SATA Express devices, or 6 SATA devices, or any combinations in between.
Depending on how many drives you intend to use in your system, this may or may not be sufficient. The stacked side-facing SATA ports also may prove to be troublesome. In tight cases, you may not be able to access the lower SATA Express port, depriving you of the opportunity to attach a SATA Express device, or two SATA devices.