SL6BY is a later and better step than SL657.

Thanks! Today I learned about core stepping.

I'm just saying that's probably the reason why the guy charges one buck twenty cents extra for the SL6BY 😐 .

I went to the intel website and read their explanation so now i understand.
http://www.intel.com/support/processors/sb/CS-001665.htm

And your explanation makes sense. Why get the older version when you can have the more recent one? But oh, gonna cost you a Buck more!

Core stepping selection has its advantages.

For instance the AMD Phenom II Deneb step C2 can only reach ~3.8GHz, and with lots of voltage; C3s reach ~4.1GHz, with less voltage.

If you plan to overclock hard that extra $1.20 could be a good investment.