How do you solve a problem like that of the Intel Core i9-9900K's demands? Adding two extra cores to the Coffee Lake architecture meant it should automatically convert an extra 33 percent of power into heat. But Intel didn’t stop there. It also reverted to old-fashioned solder to join the CPU's core to its heat spreader, helping to eliminate the heat but doing nothing about the power requirement. And that worked so well that Intel decided to allow overclocking. With a core voltage limit that exceeds what we use to overclock, it’s hardly a shock that some boards come up a little short here. But before you write off the C9Z390-CG-IW, you’ll want to read the full story.
Supermicro C9Z390-CG-IW Specifications
10Gbps: (1) Type-C, (3) Type A
(1) Gigabit Ethernet
Legacy Ports / Jacks
Other Ports / Jack
(1) v3.0 (x16, x8/x8 via riser card)
CrossFire / SLI
✗ / ✗
(1) PCIe 3.0 x4
(1) 10Gb/s Type-C
Chassis Intrusion, PC (Beep code) Speaker
FP-Audio, OC Header, TPM, SATA DOM power, RGB-LED
Internal Button / Switch
✗ / ✗
|Wi-Fi / Bluetooth|
Intel 9560 802.11ac 2x2 (1.73Gb/s) / Bluetooth 5
|HD Audio Codec||ALC1220|
|DDL / DTS Connect||✗|
Cramming a bunch of cores into a small space is nothing new, as we saw in our X99 and X299 Mini-ITX reviews, but the new Core i9-9900K is a different beast. First of all, hardly any enthusiast motherboards are power throttling it to its rated 3.6GHz to get it under its rated 130W thermal envelope under heavy loads. Second, most of the motherboards with an LGA 1151 socket that support it are based on previous designs meant only to handle the prior top-mainstream model, the Core i7-8700K.
We never got the opportunity to test the predecessor to Supermicro's new C9Z390-CG-IW, but our review sample's 7-phase voltage regulator certainly looks the part of a previous-generation mainstream board. Tiny sinks on those transistors (MOSFETs) do little to convince us of its Core i9-pushing power, but we’re hoping for a surprise larger than that of the 12-LED background RGB that spills from under the board’s leading edge.
Come to think of it, we already spotted one surprise in the board's M.2 storage slot, which fits neatly over the cutout section of its PCH sink. Most Z-series Mini-ITX boards have just one M.2 slot on the back, but the C9Z390-CG-IW has slots on both its back and front. And while both PCIe 3.0 x4 slots are designed to hold 80mm M.2 drives only, the rear one adds an SATA interface to support legacy drives.
The I/O panel includes a PS/2 port for legacy peripherals, two USB 3.1 Gen1 ports (aka USB 3.0), DisplayPort 1.2 and HDMI 2.0a, four USB 3.1 Gen 2 ports (including one Type-C), Gigabit Ethernet via Intel’s i219V PHY, 1.73Gb/s Wi-Fi via Intel’s 9560 CNVi PHY, six analog audio jacks and a digital optical audio output. A couple more USB ports would have been handy for power users, but we instead find a jumper in the panel’s only vacant space.
The jumper allows the board to force the PCIe x16 slot to function in x8/x8 mode for use with double-slot riser cards, which sounds incredibly practical coming from a company that cut its teeth on server parts. Making the switch still requires that the CPU support PCIe bifurcation, but that feature is common to all Intel's Core i9, i7 and i5 CPUs that use the LGA 1151 socket.
A few of the C9Z390-CG-IW’s headers are designated for factory use or undocumented, but there are USB 3.1 and 3.0 front headers located above and before the top-side M.2 storage interface, along with front-panel audio in front of the I/O audio jacks, a TPM header in front of the PCIe x16 slot latch, as well as an RGB strip and two fan headers on the top edge. Oddities include an OC mode jumper under the PCIe x16 slot’s lower edge, an SATA Disk-On-Module power header in front of the TPM header and a Supermicro-specific front-panel LED/button section between the two fan connectors that includes an output for an overheat/fan failure LED.
The C9Z390-CG-IW includes a printed manual, driver disc, I/O shield, cable label stickers, two Wi-Fi antennae and two SATA cables.
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