ECC logic is implemented in the memory controller (in the CPU these days). The ECC DIMM just provides extra chips to store ECC bits. And the motherboard, if it

ECC logic is implemented in the memory controller (in the CPU these days). The ECC DIMM just provides extra chips to store ECC bits. And the motherboard, if it supports ECC, provides just extra data lanes that connect the extra DIMM chips to the appropriate pins on the CPU.