Yes I understand binning and no I'm not going to read your boring links. LOL
Any 920 will run 4ghz, let alone 3.3ghz, so you would pay another $721 for a higher binned processor that runs slower? FAIL
Why are you asking this question? If you are a PC enthusiast you should know why people buy them. Think of it in these terms:
Why do people spend $5K+ on a Alienware PC that would cost them $1500-$2K to build? Because they are newbies and don't have the experience.
So for this guy, maybe he wants a CPU thats over 3GHz without having to OC in the Core i7 series of CPUs thus the Core i7 975 is the best for him.
For the OP and what mobo, anything Asus. Asus never fails to deliver.