I don't know the difference but w/e they say its slightly faster :P
I'm only 17 and I have nothing better to do with my money. Well I do but I don't care I got a house and food provided for me for the next year :P
If you are going to be overclocking, the 875k will beat it by a mile. You only put stress on the CPU by increasing the multiplier meanwhile the other i7's that aren't "k" or "extreme" need to be overclocked by raising the front side bus which puts stress on the entire system, potentially causing component failures such as in RAM and the motherboard.