ECC error correction:

The error correction code ECC (Error Correction Code) is primarily used in high-end PCs and file servers. The key difference between ECC and parity checking is that ECC is able to identify and correct 1-bit errors. Normally, when using ECC, 1-bit error correction occurs without the user even noticing that an error has occurred. Depending on the type of memory controller, ECC can even detect rare 2-, 3-, or 4-bit memory errors. Although ECC detects these multi-bit errors, only 1-bit errors can be corrected. If ECC identifies a multi-bit error, a parity error is reported.

Using a special algorithm (mathematical sequence) and in cooperation with the memory controller, ECC adds ECC bits to the data bit, which are then stored together in memory. When data is requested from memory, the memory controller decodes the ECC bits and checks whether one or more data bits are corrupted. If there is a 1-bit error, the bit is corrected by ECC. In the rare cases of a multi-bit error, a parity error is reported (as previously mentioned).

Registered RAM modules:
With "Registered" memory modules, the registers for memory addressing are contained directly on the module. This makes it possible to equip a server with larger memory capacity.