How does the 9684X differ from the standard EPYC 9654?

Both have 96 Zen 4 cores, but the 9684X adds 3D V-Cache for 1152 MB of L3 versus 384 MB on the 9654. The 9654 runs at higher clocks, so it wins on lightly threaded work while the 9684X wins on cache-heavy workloads.

What socket and memory does it need?

It uses AMD's SP5 socket (LGA 6096) and pairs with DDR5 memory on Genoa platforms, not DDR4. Plan on a compatible server board and BIOS that lists the 9684X.

Is it worth it over a cheaper EPYC model?

Only if your software is bound by cache misses, such as EDA, simulation or large databases. For general virtualization or web serving, a standard Genoa chip with higher clocks usually gives more for less.

How much power and cooling does it need?

It is a high-TDP part, so it needs a server chassis and heatsink rated for its socket power. Confirm the board and cooling support the configured TDP before ordering.