CREATE TABLE table_27765443_2 (model___computer_name VARCHAR, cpu_type VARCHAR)

Name the total number of model for amd opteron dual-core 2.6ghz
SELECT COUNT(model___computer_name) FROM table_27765443_2 WHERE cpu_type = "AMD Opteron dual-core 2.6GHz"
SELECT COUNT("model___computer_name") FROM "table_27765443_2" WHERE "AMD Opteron dual-core 2.6GHz" = "cpu_type"