Error Correcting something-or-other [Code (?)] It uses an extra parity bit to check and correct the bytes. I do not think that Macs use ECC chips. So, you do not heed the extra expense. You can call the friendly folks at http://www.datamem.com/ for more detailed explanations. Their site also lists memory needs for any device or CPU that you have in mind (for example, I got extra memory for my HP 2500 Color Laser Printer there). --Steve At 10:01 AM -0500 8/17/03, mentholiptus wrote: >Can someone explain what "ECC" as opposed to "non-ECC" means when >purchasing memory? Will "non-ECC" memory work in a G4/G5?