The Gigabyte B850 GAMING X wins in 6 out of 14 comparable specs, with 3 ties. Its biggest advantage is Max Memory (100% better).
ROG STRIX Z590-E GAMING WIFI wins in 5 specs (USB Type-C: 100% better).
Recommendation
Choose B850 GAMING X if you want the best overall performance — especially max memory.
Choose ROG STRIX Z590-E GAMING WIFI if usb type-c matters more to you.
