Technically, 7-7-7 is a JEDEC CAS latency standard for DDR3-1333 memory. However, very few such modules ever manufactured had their SPDs programmed to set 7-7-7 at 1333MHz; such modules have always been ridiculously expensive. Instead, most so-called "DDR3-1333 CL7" modules do not use native DDR3-1333 parts - but instead they use overclocked DDR3-1066 parts with their SPDs programmed to auto-set nothing higher than 1066MHz. As a result, the only native DDR3-1333 memory modules sold as such at a reasonable price are all CAS 9 (9-9-9). Blame the memory manufacturers and the economy for this mess.
That makes a lot of sense. Thanks for explaining