The AMD Ryzen 7 7800X3D supports DDR5 memory, and it is compatible with AMD EXPO technology, which can enhance memory performance.

For the G.Skill Trident Z5 RGB DDR5 memory at 6400 MHz, here are the key points to consider:

- The Ryzen 7 7800X3D supports DDR5 memory, and AMD EXPO technology is compatible with this CPU.
- While the CPU can handle high-speed DDR5 memory, the optimal performance for the 7800X3D has been noted to be around DDR5 6000 MHz with a CL30 timing. However, it should still support 6400 MHz speeds, although it might not be the optimal configuration.

In summary, yes, the Ryzen 7 7800X3D will support the G.Skill Trident Z5 RGB DDR5 memory at 6400 MHz with AMD EXPO, but for the best performance, DDR5 6000 MHz with CL30 timing is recommended.