Unbuffered ECC vs Registered ECC for Threadripper: Unbuffered ECC works, registered won't fit

Threadripper’s memory controller only accepts unbuffered ECC (UDIMMs), while registered memory (RDIMMs) won’t physically fit in the slots. The confusion comes from older server platforms where ECC automatically meant registered — on consumer TR4, it’s UDIMMs only. Grab 3200 MHz unbuffered ECC sticks, enable it in BIOS, and you’re set. Registered memory is for Epyc and Xeon.