Oh noes RMA the processor you got a B3 stepping!
Just joking... a friend recently was researching a very similar build and he asked about G0 and B3 steppings because people had been making a big splash about it on forums, etc. It cracks me up how even people who just do light overclocking get so into such minor details.
I didn't care either way. I just figured I'd point it out since some people were talking about it earlier.