Size of the chip in megabits. For example, 256 Mbit, or 32 MB chip. Nearly all motherboards only recognize 1 GB modules if they are low density 64M×8 modules. If high density 128M×4 1 GB modules are used, they most likely will not work. The JEDEC standard allows 128M×4 only for slower buffered/registered modules designed specifically for some servers, but some generic manufacturers do not comply.