GamersNexus had the opportunity to visit one of Gigabyte's factories in Taiwan, and shot a video that illustrates how motherboards and video cards are made. The production of a motherboard apparently takes about an hour, with half of the work performed by automated SMT lines. The other half contains of large component installation and manual quality checks.
Motherboard manufacturing is a refined process, but each board still takes upwards of an hour to finalize on the assembly line. About half of the assembly is now done by automated SMT lines, with the rest being manual quality checks and large component installation (like PCIe slots). As for how to make a video card, it follows exactly the same process -- the difference is just which board is being fed through the machines on each day.
This factory is located on Nanping Road in Taiwan, about a 40-minute drive from Taipei 101. Other electronics factories and SMT lines exist predominantly in China, like in Shenzhen, but Gigabyte has shifted operations toward its Taiwan-based factory to help dodge potential incoming tariffs. The company also focuses its higher-end product manufacturing on this line.