HardwareSecrets checked out the ECS factory in ShenZhen, mainland China. Here's a snip from their tour report:
We visited ECS factory located in ShenZhen province (the correct pronunciation is “tchen-jen”), in mainland China. This trip was a unique experience in several ways and we think it is worthwhile to talk more about several aspects of this trip – and about the factories, of course. We visited two factories: ECSM (ECS Manufacturing), which is a giant two-building complex where motherboards, notebooks and other components are manufactured, and Biloda, which manufactures printed circuit boards (PCBs) used on ECS and PCChips motherboards (for those who doesn’t know, PCChips belongs to ECS).