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Crucial makes some 16GB low profile DDR4 UDIMMs, but they're ECC. ECC will usually work just fine in consumer boards (without any of the actual ECC functionality, mind you) but it's not guaranteed. If you can get them from somewhere with a generous returns policy you could give them a try. Just make sure to get the UDIMMs: Registered DIMMs (RDIMMs) are easier to find, but absolutely will not work at all in consumer boards.