I think the title explains it all Running win 7 Gigabyte Mobo X6 1055t 4gb ram passes memtest86+ Good PSU And yes the cpu fan header is connected. Is it just a bad install?
CPU fan not spinning is a really bad sign. I'd say the motherboard is defective. OS has nothing to do with it. Have you checked for a MB Bios update?
AMD CPUs will fry quickly (less than a minute) without CPU fan. Unless you're sure your CPU has thermal shutdown circuitry I'd find another motherboard - pronto.