According to the Realtek RTL9210B product page , the chip features the following specifications:
Unlike cheaper JMicron controllers (JMS583), the RTL9210B has a reputation for stable thermal performance. It supports PCIe Gen3 x2, which is sufficient to saturate the 10Gbps USB cap without generating the excessive heat of older Gen3 x4 bridges. rtl9210b datasheet
The RTL9210B is notable for its active third-party developer community, which has filled in many of the gaps left by the official documentation. According to the Realtek RTL9210B product page ,