CREATE TABLE table_25839957_5 (shader_model VARCHAR2, core_clock___mhz__ VARCHAR2)

How many shader models have a 900 core clock ( mhz )?
SELECT COUNT(shader_model) FROM table_25839957_5 WHERE core_clock___mhz__ = "900"
SELECT COUNT("shader_model") FROM "table_25839957_5" WHERE "900" = "core_clock___mhz__"