Does the Z790 use DDR4 or DDR5?

Z790 boards exist in both DDR4 and DDR5 versions — the chipset supports either, so check the specific board model before buying memory.

Not compatible

Is the Ryzen 9 7900X compatible with Z790?

No — not compatible: Ryzen 9 7900X + Z790. Socket mismatch: CPU is AM5, motherboard is LGA1700. Live eBay prices for both.

Spec

Ryzen 9 7900X

Z790

Socket

AM5

LGA1700

Peak power

230W

—

Memory

—

DDR4 or DDR5 (board variant)

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Ryzen 9 7900X

Z790

Socket mismatch: CPU is AM5, motherboard is LGA1700. The sockets differ, so the CPU will not fit this board.