With the release of the 12th generation Intel Core processors (Alder Lake), a new processor socket was introduced. The LGA 1700 socket also supports Intel's 13th generation processors, codenamed Raptor Lake. The LGA 1700 socket features 500 more pins than the 1200 socket. These additional pins are used by Intel's latest processors to support DDR5 memory and PCIe 5.0. To accommodate the contacts, the CPU layout has been changed from square to rectangular.
Since Intel Core CPUs of the 12th and 13th generations support both DDR4 and DDR5 RAM standards, many manufacturers offer LGA 1700 motherboards with DIMMs for either DDR4 or DDR5. Unlike USB or PCIe, the DIMM slots and RAM modules are not backward compatible! Therefore, if you want to run your Core i9-13900K with DDR5 RAM, you need an LGA 1700 motherboard with DDR5 DIMM slots.
Intel Core CPUs based on the hybrid core architecture provide up to 16 PCIe 5.0 lanes. Accordingly, many motherboards with socket 1700 offer a PCIe x16 slot that is connected to the CPU with up to 16 lanes. In some exceptional cases, the 5.0 lanes could also be used to connect SSDs or other expansion cards.
