You can get ECC UDIMMs from Supermicro. They are rebranded Micron DIMMs. ECC memory is not going to go as high of frequencies as you might be looking for. They will only go up to the officially validated speed of the CPUs. https://store.supermicro.com/16gb-ddr4-mem-dr416l-cv02-eu26....
The rated speeds are not as high, but ECC memory can be overclocked just as non-ECC; memory overclock support is mostly up to the motherboard. I have some DDR4-2666 ECC overclocked to 3200 MHz with slightly tighter timings on TRX40.
