Die Boardmaße
* ATX: 305 mm × 244 mm (12″ × 9,6″).
* Mini-ATX: 284 mm × 208 mm (11,2″ × 8,2″)
* Micro-ATX: 244 mm × 244 mm (9,6″ × 9,6″)
* Flex-ATX: 229 mm × 191 mm (9″ × 7,5″),
* Mini-ITX: 170 mm × 170 mm (6,7″ × 6,7″)
* Nano-ITX: 120 mm × 120 mm (4,7″ × 4,7″)
* Pico-ITX: 100 mm × 72 mm (4″ × 2,8″)
* E-ATX-Format: 305 mm × 330 mm(12″ × 13″)
Google helps and :p
wikipedia knows all