The MSI MEG Z890 ACE is the objective winner of this comparison, securing victory in ten out of thirteen evaluated specifications. Its most impactful advantage is a 300% increase in maximum memory capacity compared to the alternative. While the Gigabyte B660M DS3H DDR4 holds a 100% advantage in the number of available PCIe x1 slots, it falls behind the MSI MEG Z890 ACE in the majority of technical categories measured.

Users prioritizing high-capacity memory configurations should select the MSI MEG Z890 ACE for its superior support in that area. Conversely, the Gigabyte B660M DS3H DDR4 is the appropriate choice for builders who specifically require additional PCIe x1 slots for their expansion needs. Each motherboard serves distinct hardware requirements, so the decision should depend entirely on whether your build demands expanded memory overhead or increased connectivity for PCIe x1 peripheral devices.