user: Question: Name the total number of model for AMD Opteron dual-core 2.6GHz
Columns: ['Model - Computer name', 'CPU type', 'No. of processors', 'Period of operation', 'Maximum peak performance ( Teraflops )', 'Use']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Cray XT4 - La Dôle', 'AMD Opteron quad-core Barcelona 2.3GHz', '160 (640 cores )', 'May 2007 - June 2012', '5.88', 'Numerical weather prediction ( MeteoSwiss )']
SQL:

assistant: SELECT COUNT("Model - Computer name") FROM "Table" WHERE "CPU type" = 'AMD Opteron dual-core 2.6GHz';