The Gigabyte Z890 AORUS MASTER is the objective winner of this comparison, securing victory in eight out of thirteen evaluated specifications. Its most impactful advantage over the ASRock H670 Steel Legend is its maximum memory capacity, which is 100% higher. While the ASRock H670 Steel Legend holds a 200% advantage in the number of PCIe x1 slots, the superior memory ceiling makes the Gigabyte Z890 AORUS MASTER the more robust option for high-capacity system configurations.

Users who prioritize extensive memory support for demanding workloads should choose the Gigabyte Z890 AORUS MASTER for its significantly higher capacity. Conversely, the ASRock H670 Steel Legend is the better selection for builders who require a higher quantity of PCIe x1 slots for specialized expansion cards. Your final decision should depend on whether your specific build requirements prioritize total system memory overhead or the physical connectivity provided by additional expansion slots.