New Intel CPUs usually mean new motherboards, and MSI is diving into Coffee Lake with confidence. The company has at least a baker's dozen of Z370 boards ready to go for prospective Coffee Lake builders, and the Z370 Gaming Pro Carbon AC is the last stop so far before one ascends to the Z370 Godlike Gaming in the lineup.
MSI is using the transition to Z370 as an opportunity to freshen its mainstream boards' styling cues. The Pro Carbon still takes after automotive themes, but I daresay it's grown up a bit since our experience with its Z270 cousin. No, we're not looking at real carbon fiber on this board's I/O shroud, but the subtle patterning on these accents is pleasant-looking enough.
I wish the company had lacquered over these accents for additional flair as it does on its higher-end Pro Carbon boards, but that's an entirely personal preference. Even without that gloss, the MSI and Pro Carbon logos screened onto the board's chipset heatsink and I/O shroud seem like they were applied at Maaco instead of in a pro's paint shop. Maybe this is a sample defect, since other Pro Carbons I've seen in the wild have cleaner, more vivid white logos.
Compared to its predecessor, the Z370 Pro Carbon gets sportier-looking heatsinks covered with streamlined plastic accents. Pretty swanky. The downside of this new look is that the Pro Carbon's heatsinks seem to give more to form than to function. Neither chunk of metal is particularly large, and they're both partially covered by the plastic shroud that runs over them. That shrouding could reduce the effectiveness of these 'sinks.
That partial coverage is especially concerning given the limited surface area afforded by the smooth and river-rock-like primary VRM heatsink to the left of the socket to begin with. This heatsink does have a few ridges and notches to break up its uniform surface, but again, those features seem mostly cosmetic instead of functional when you compare them to past generations of motherboard heatsink designs.
MSI also constructs the Pro Carbon's heatsinks in a somewhat unusual fashion. The black secondary VRM heatsink is one piece of solid metal, but the silver primary heatsink uses a screw-in base plate to effect thermal transfer from the board's primary voltage regulators to its metallic mass. Out of the box, this plate is coupled with the heatsink above by a modest smear of thermal interface material.
This construction method probably won't make or break the performance of this heatsink, but it's the first time we've seen such an arrangement in recent memory. (We conducted our thermal and overclocking testing before dissassembly, so our later comments will reflect the board's out-of-box performance.)
I bring all this up because Intel's highest-end Coffee Lake CPUs will demand more power from a motherboard's VRMs than ever. These chips offer the highest number of potential cores and threads ever in a mainstream Intel socket. We've already seen evidence that an overclocked Core i7-8700K can get even a high-end power-delivery design with active cooling close to its thermal limits. We'll see how the Pro Carbon AC handles a similar load in our overclocking tests.
Under those heatsinks, MSI relies on separate high- and low-side VRMs from ON Semiconductor plus a PWM controller from uPI. MSI chose ON Semi NTMFS4C024N MOSFETS for the board's high-side switching duties and NTMFS4C029N MOSFETs with 46A ratings for its low side. Strangely enough, that PWM controller isn't part of the components cooled by the board's VRM heatsinks.
Although public documentation isn't available for the uPI 9508Q PWM controller that MSI selected, the presence of three uPI MOSFET driver chips on the back of the board and another among the front-mounted VRM circuitry suggests the chip is capable of a 4+2-phase native topology.
Many boards include integrated Wi-Fi and Bluetooth using an M.2 slot these days, but MSI sticks to a pack-in PCIe x1 card to give the Pro Carbon its AC suffix. I laud the company's choice of an Intel 8265N radio for wireless duties, but I do wish it had gone to the expense of wiring up an M.2 slot in the board's I/O cluster instead of using a riser card. Burning a PCIe slot on what's often a built-in feature might not sit well with the expansion-hungry.
In the memory department, MSI offers four DIMM slots capable of holding up to 64GB of RAM. MSI officially touts DDR4 multipliers ranging up to 4000 MT/s, but the Coffee Lake memory controller is capable of far higher speeds for extreme overclockers. Next, let's take a look at the board's expansion resouces and audio subsystem.