High end or mainstream? That's the broad choice you have to make when building a powerful Intel-based desktop these days. The Haswell-E platform sits comfortably at the high end, an offshoot of its dual-socket Haswell-EP brother. The name of the game here is high core counts, massive memory bandwidth, and dozens of PCI Express lanes. If this high-end platform has a drawback, it's that the -EP release cycles can leave your choice of processor one microarchitecture generation behind what's available on the mainstream platform.
So, what do you do if you want an abundance of PCIe lanes, but you also want your system to sport the latest Skylake cores? Gigabyte's Z170X-Gaming G1 motherboard just so happens to tick those two boxes. Selling for $473 at Newegg right now, the Gaming G1 sits right at the top of Gigabyte's Z170 lineup. It's products like this one that really let Gigabyte's engineers show off what they can do. Let's start digging in.
The Gigabyte Z170X-Gaming G1 qualifies for the E-ATX club, thanks to its 10.4" (26.4 cm) width. That makes for 8% more board area compared to the G1's standard ATX counterparts, and the extra room lets Gigabyte pack in components (and functionality) without making the board overly cramped.
The basic red-and-white-on-black color scheme that we saw on Gigabyte's more affordable Z170X-Gaming 7 carries over to the Gaming G1, as well. This board has fancy white SATA ports covered with an LED-backlit metallic shroud, something the Gaming 7 can't boast. Otherwise, this board has the same snowy accents, white plastic port shroud, and pure black PCB of its less-expensive sibling. The Gigabyte-exclusive "Durablack" Nippon Chemi-Con capacitors give the CPU socket area a nice blacked-out look, too.
That prominent plastic shroud is made up of two separate pieces, the largest of which hangs over the left VRM heatsink and the rear port cluster. The smaller portion offers a glimpse at the fancy WIMA capacitors for the board's audio setup, as well as the LED Trace Path lighting below. For those who aren't fans of the look, these pieces can be removed with a handful of small screws on the underside of the board. Removing the shrouds could also improve airflow over that left VRM heatsink. We left the fancy body kit in place during our testing, though.
Skylake eschews the fully-integrated voltage regulator (FIVR) used by Haswell chips, so it falls to the motherboard's VRMs to supply each of the processor's input voltage rails. Gigabyte has gone all out with the Gaming G1's power delivery system. A 22-phase VRM setup hides under two heatsinks. 16 of these phases are for the CPU, four are for the on-die graphics, and the remaining two are for the system agent and I/O.
Gigabyte uses International Rectifier's digital PWM controller and PowIRstage ICs in this board's power delivery system. PowIRstage combines the three components of a power phase—the driver, high side MOSFET, and low side MOSFET—into a single package. This setup potentially offers higher efficiency and better thermal performance than a VRM whose power phases use discrete components.
The VRM heatsinks—along the top and to the right of the CPU socket—are a hybrid design with built-in G1/4" threaded fittings ready for water cooling. The embedded water channel in these two heatsinks ensures that the VRM components won't get too hot and bothered when the heatsinks are plumbed into a liquid-cooling loop. More heatpipes snake their way through the heatsink on the left. Underneath this heatsink is a
PLX Avago PEX 8747 48-lane PCI Express switch. The heatpipes snake all the way down to the PCH heatsink, too, so liquid-cooling the VRMs also helps to cool those two chips.
Liquid-cooling isn't a requirement, of course. The heatsinks work fine air-cooled, and that's how we ran the board for our testing. All of the heatsinks are firmly secured to the board with screws to ensure that they make good contact with the components beneath.
The CPU socket on the Gaming G1 is more crowded than we'd like. The left heatsink is the most troublesome. Even with a height of just 22 mm, its close proximity to the socket meant it ran afoul of the hose connections to the water block of our Cooler Master Nepton 240M. Despite their 29-mm height, the other two heatsinks stay out of the way.
Thankfully, Gigabyte's engineers put more distance between the CPU socket and the DDR4 DIMM slots. The company recommends installing DIMMs in the red slots first. For builders who are only installing two sticks, using the red slots gives maximum clearance between the processor's heatsink or water block and the DIMMs. Thanks to DDR4's higher-density modules, up to 64GB of RAM can be installed on the Gaming G1 with all four slots populated. Gigabyte uses slots with locking mechanisms on only one end, which can make life easier when swapping DIMMs in crowded cases.
Since LGA1151 retains the same mounting mechanism as Haswell's LGA1150 socket, be sure to check for adequate clearance around the socket first if you're planning to use an oversized CPU cooler. Here are some measurements to help you figure out which components can safely fit together on the board:
The Gaming G1's four PCIe 3.0 x16 slots are arranged to accept a quartet of double-wide video cards. To pull that feat off in a standard-height ATX board, Gigabyte had to put a PCIe x16 slot in the topmost position. This layout puts the first video card in closer proximity to the processor than we'd like. To make matters worse, the PCIe switch chip and its heatsink are sandwiched between the top PCIe x16 slot and the CPU. These decisions make for a fairly cramped socket area. At least the heatsinks are all shorter than 30 mm.
A total of five fan headers are situated within easy reach of the CPU socket: two CPU fan headers and three more for system fans.
To feed those PCIe x16 slots, Gigabyte uses an Avago 48-lane PCI Express Gen3 switch. This switch is set up so that sixteen of its lanes function as upstream links connected to the Skylake CPU's Gen3 PCIe lanes. The remaining 32 Gen3 lanes function as downstream links, supplying the four x16 slots.
With two graphics cards installed in the first and third x16 slots, each card gets sixteen lanes for a x16/x0/x16/x0 arrangement. That slot spacing gives two beastly triple-wide graphics cards one slot's worth of breathing room. Adding a third video card in the second or fourth x16 slot will force either the first or third slot to run with eight lanes, for either a x8/x8/x16/x0 or a x16/x0/x8/x8 arrangement. Using all four PCIe x16 slots creates an x8/x8/x8/x8 arrangement. Two groups of four ASMedia ASM1480 multiplexers handle the lane switching. You can spot them above the left and middle PCIe x1 slots.
The Gaming G1 can support two-, three-, and four-way SLI or CrossFire configs. Provided your case has an extra slot's worth of room below the board, you can install as many as four double-wide video cards. To help you on your way to such an absurd build, Gigabyte includes two-, three-, and four-way SLI bridges, along with a single two-way CrossFire connector.
Peppered around those four x16 PCIe slots, we find three x1 slots. These slots aren't connected to Gen3 lanes from the chipset. Instead, they're connected to an ASMedia ASM1184e PCI Express Gen2 switch chip. This PCIe switch's single upstream port is connected to one chipset lane, and three of its downstream ports feed the PCIe x1 slots. That's right: these are Gen2 x1 slots, rather than Gen3. The fourth downstream port from the ASMedia switch is connected to the board's two left-most SATA 6Gbps ports, labeled GSATA3 8/9.
Here's a graphical representation of the G1's expansion slots. It shows how each one is connected to the platform's PCIe lanes:
The stainless steel shielding on the PCI Express x16 slots isn't just for show. Gigabyte has reinforced these metal shields with extra anchor points on the board. We're told this setup makes the slots 1.7 times stronger in the face of shearing stresses and 3.2 times stronger in retention tests. This setup could help to prevent damage to the slots if you're transporting a system that has a gargantuan video card or four.
Now that we've looked at this board's CPU socket and expansion slots, let's move on to the Gaming G1's storage subsystem.