Supermicro C9Z390-CG-IW Review: 9900K Meets Mini-ITX


Recent years of developing a consumer-friendly UEFI has resulted in an EZ Mode GUI from Supermicro, along with advanced settings available via the keyboard’s F7 function. Users unfamiliar with overclocking can still set boot order and enable XMP memory profiles from EZ Mode. Charging straight into Advanced mode, we found an Overclocking menu that presented CPU, Memory, Graphics and Voltage submenus.

The CPU Overclocking submenu includes basic overclocking configurations for:

  • 4.3 through 4.6GHz using a 1.3V CPU core, 1.3V System Agent and 0.95V CPU I/O
  • 4.7 and 4.8GHz using 1.35V CPU core, 1.30V System Agent and 1.2V CPU I/O
  • 4.9GHz at 1.4V CPU core, 1.35V System Agent, 1.2V CPU I/O and Level 4 Load Line Calibration
  • 5.0 through 5.5GHz using 1.45V CPU core, 1.4V System Agent, 1.2V CPU I/O and Level 4 Load Line Calibration

Since our CPU overheats at 1.35V, we started with the 4.6GHz setting and worked our way up to 4.94GHz at 49 x 101 MHz.

Default power limits were insanely low, and even overclocking modes don’t appear to be designed with an 8-core, 16-thread CPU in mind. We increased both CPU power limits (second image above) to the motherboard’s limit to prevent overcurrent protection from resetting the board.

The DRAM conundrum should feel familiar to old-time overclockers: Setting XMP profile blocks out individual timings and data rate. Switching from Default to Custom memory profile allows users to tweak everything from Default baselines, and switching from XMP to Custom memory profile allows users to tweak everything from XMP baselines. Unfortunately, users who don’t know what to set for all 66 adjustments aren’t likely to get very far, as only seven of those can be configured to automatically adjust based on a manually selected data rate.

The Load Line Calibration feature adjusts voltage upward in response to it dropping under heavy software loads. We found that the easiest way to get 1.3V CPU core when using 16 threads of Prime95 (small FFTs) was to choose a 1.285V core setting and Level 2 Load Line Calibration. Concerning Load Line Calibration, Level 1 put our core voltage through the roof, while Level 3 allowed it to drop well below our desired operating level.

The non-overclocking menus for CPU and Memory settings allow users to make non-overclocked adjustments. We enabled all of the CPU’s power-saving features for comparative benchmarks and power measurements but not for overclocking evaluation.

RGB control is found within the Boot Feature submenu of the Advanced menu. However, "on” and “off” are its only modes, and the only “on” profile is a fast-flashing rainbow mode.

The C9Z390-CG-IW has only two fan headers, and both of those support PWM-based settings only. Automatic modes appear to control a three-pin RDM1225S, despite the PWM-based settings of manual profiles.

The Save & Exit menu includes everything from boot settings to two registers where users can save their firmware configuration as profiles. The board defaults to AHCI storage mode and must be manually configured to access UEFI-enhanced OS installations.

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