I bought a Biostar Mobo 945GC-m4 specifically because it was a socket 478 and I had a 2.6 ghz cpu lying spare. Wanted a cheap system to play around with Linux distos. Nowhere on the box, or on NewEgg which is selling it, does it say CPU support is limited to 7 specific CPUs. Mine isn't one of them and the board won't post. The install guide says the board supports 3xxx CPUs. but their web site has specific part numbers listed. My question is, are all 478, 3.0 ghz CPU's created equal? Is the part number more related to where it was made than what internal architecture it runs?
No... the part number is related to the specific model of the CPU and more so related to it's Stepping (revision level). There can be changes within the revision such as going from one being 125 TDP & another 95 TDP. This can cause one to work on your motherboard, while the other won't.