https://wccftech.com/intel-comet-lake-s-10-core-cpu-400-series-motherboards-new-lga-socket/

It looks like Intel’s upcoming Comet Lake-S processors would end up being supported on a new socket, ending backward compatibility on existing motherboards. According to the latest leaks & listings within the new Intel server chipset driver, there are at least two chipset generations after 300 series that are planned for launch for next-generation processors.

The listing in the new Intel chipset driver mentions the 400 series chipset family and the 495 series chipset family. Currently, the 8th and 9th Generation family are compatible with 300 series boards which feature the LGA 1151 V2 socket. The LGA 1151 V2 socket was a revised version of LGA 1151 V1, featuring a different pin layout and configuration (more here). This meant that while the 6th & 7th Gen CPUs ran on LGA 1151 V1 socket, they couldn’t run on LGA 1151 V2. Similarly, 8th and 9th Gen CPUs weren’t backward compatible.