I've been thinking about RAM sizes lately and wonder: does advertised RAM size include the bits used for Parity or ECC?
Generally, ECC is 8 bits for every 64 bits of data. Does that mean that ECC takes up 8/(64 + 8) = 1/9 of the total RAM size? For example, if I'm looking to buy 4 GB of RAM, am I really getting 3.56 GB of usable RAM with 0.44 GB of it taken by ECC? Or does that mean I'm getting 4 GB of RAM that has an additional 0.5 GB for ECC?
Generally, ECC is 8 bits for every 64 bits of data. Does that mean that ECC takes up 8/(64 + 8) = 1/9 of the total RAM size? For example, if I'm looking to buy 4 GB of RAM, am I really getting 3.56 GB of usable RAM with 0.44 GB of it taken by ECC? Or does that mean I'm getting 4 GB of RAM that has an additional 0.5 GB for ECC?