Some of the storage capacity is used for formatting and other purposes and is not available for data storage. 1GB equals 1 billion bytes. Not all capacities available at initial launch.
Typical I/O performance numbers as measured using CrystalDiskMark with a queue depth of 32 and write cache enabled. Fresh out-of-box (FOB) state is assumed. For performance measurement purposes, the SSD may be restored to FOB state using the secure erase command. System variations will affect measured results.