CREATE TABLE table_25839957_5 (core_clock___mhz__ VARCHAR2, memory_bandwidth___gb_s__ VARCHAR2)

What core clocks ( mhz ) have a 21.3 memory bandwidth ( gb/s )?
SELECT core_clock___mhz__ FROM table_25839957_5 WHERE memory_bandwidth___gb_s__ = "21.3"
SELECT "core_clock___mhz__" FROM "table_25839957_5" WHERE "21.3" = "memory_bandwidth___gb_s__"