Storage, sound, and lots of legacy
The SLI Plus' SATA ports all reside in its bottom-right corner, along with its USB 3.0 internal header.
MSI has foregone SATA Express connectivity on this board. Instead, it's opted for six regular SATA 6Gbps ports. That decision doesn't really bother us, since there are practically no SATA Express storage devices on the market. It would have been nice if all of the SATA ports were right-angled, though, especially in the age of lengthy graphics cards. At least the leftmost internal USB 3.0 header is right-angled. That design choice should prevent the bulky USB 3.0 front-panel cable in most cases from interfering with longer graphics cards.
The Z170A SLI Plus ticks the next-gen storage box with a single M.2 slot, found between the topmost PCIe x16 slot and the CPU socket. Unfortunately, this position places the installed SSD between two potentially large heat producers. This heat could cause some M.2 SSDs to get too toasty—Samsung's SM951 PCIe SSD already throttles itself even without a graphics card in play, for example. Still, this slot position is better than putting an M.2 SSD directly under a graphics card.
The M.2 slot accepts mini-SSDs up to 80 mm long, but only PCIe SSDs will work here—SATA gumstick drives need not apply. MSI also supports U.2 PCIe storage devices like Intel's 750 Series SSD with its Turbo U.2 host adapter card, which plugs into an M.2 slot. This adapter is sold separately.
The four Gen3 lanes that feed the M.2 slot provide it with up to 32 Gb/s (4 GB/s) of bandwidth. Those are some impressive numbers, to be sure. That said, the DMI link between the processor and the chipset is itself a highway made of four Gen3 lanes. That link puts an upper limit on all of the board's storage connectivity, including the third x16 slot.
The Z170 chipset provides immense flexibility to motherboard manufacturers, thanks to its 26 multi-purpose, high-speed I/O lanes. Up to twenty of these can be used as PCIe Gen3. In a nice change of pace however, the Z170A SLI Plus has no sharing of lanes between different storage ports. Any port or header you see on the board can be used without limitation. That saves me two paragraphs worth of rather dry writing.
The SLI Plus' rear port cluster is a mish-mash of old and new. Not only does MSI give us PS/2 mouse and keyboard ports—we also get a VGA output thrown in for good measure. These ports come alongside some brand new hotness in the form of a Type C USB 3.1 port connected to an ASMedia ASM1142 controller. This is a "real" USB 3.1 port, also known as USB 3.1 Gen2. Unlike a lot of other Z170 boards that are equipped with this same ASMedia controller, MSI chose not to include a Type A USB 3.1 port alongside the Type-C connector.
Rounding out the back panel, we get two more USB 3.0 ports from the Z170 chipset Four more USB 3.0 ports are available from two internal headers, one of which is right-angled. The Gigabit Ethernet port is powered by Intel's I219-V controller. Below this are two USB 2.0 ports, with four more available through two internal headers at the bottom of the board.
For buyers looking to use a Skylake CPU's integrated graphics processor, the SLI Plus offers a DVI-D port and an HDMI 1.4b port alongside the aforementioned VGA output. Folks with discrete graphics cards don't have to worry about the onboard display outputs, of course.
The only thing better than walls of text is overly colorful diagrams. We've broken out our crayons to draw you this port diagram:
The Z170A SLI Plus' onboard audio suite relies on Realtek's familiar ALC1150 codec. That chip is backed by dual TI OP1652 amplifiers and high-end Chemi-Con audio capacitors. MSI calls this implementation "Audio Boost".
Component selection alone doesn't ensure superior quality onboard audio, however. Just as important is the analog signal quality itself. Thankfully, MSI has taken steps to ensure that the analog audio signals are as noise-free as possible. The audio circuitry and components are isolated to their own section of the board, and the left and right channels are split between different PCB layers.
Overall, the SLI Plus' analog output was pleasing. My ears didn't detect any unwanted noise under a variety of load and idle conditions: no pops, no hissing, nothing to disturb the listening experience. That's a good thing, because the Z170A SLI Plus lacks an optical S/PDIF out port.
Just below the firmware's flash chip is an SPI header that can be used to re-flash the firmware with the right equipment, a common sight on MSI boards. This arrangement isn't as nice as having a socketed firmware chip, but it's better than nothing. One feature of MSI's more costly Z170 boards that isn't found on the SLI Plus is BIOS Flashback+. Although it's not a feature that gets used every day, BIOS Flashback+ lets builders update their firmware with nothing more than a USB thumb drive and a power supply. That feature could save builders from having to borrow a supported CPU to flash to an updated firmware.
Another gripe is MSI's omission of a front-panel wiring block. At least the board has silk-screened markings for each of the front-panel headers. You'll need a flashlight and possibly a magnifying glass to make out the text once the board is installed, but that will hopefully save you a trip to the user manual. The SLI Plus also ships with a standard stamped metal I/O shield, rather than the padded affair we usually get with higher-end boards. Keep a box of Band-Aids handy.
It's not all bad news on the niceties front, though. MSI includes some good DIY-friendly features. Three LEDs, above the ATX power connector show CPU, memory, and graphics operation during the boot process. This feature, dubbed "EZ Debug LED" can let you quickly and easily identify what is going on during POST. Another useful LED can be found between the DIMM slots and the ATX power connector. This XMP LED illuminates when your memory is running with an XMP profile enabled.
For folks who need legacy I/O options, the SLI Plus puts in an impressive showing. Not only do we get a serial port header, but we've also got parallel port support. MSI doesn't include the actual bracket headers, though, so you'll have to dig through that "miscellaneous cables" box until you find some. It's nice to know that my trusty duo of an HP Laserjet 4 and U.S. Robotics 56K modem aren't going to be left out in the cold with Skylake, at least.
Now that we've well and truly covered the SLI Plus from a hardware perspective, let's look at the board's softer side.