Reviews are freaking me out.
With the same card one goes to 1200/1450 (core/memory) from 1000/1125 mhz while others struggle at 1075/1250.
Same for the oc editions
That's because you're reading reviews on OCs, when the quality of each individual chip, even within the same exact model, can vary enough to change those results drastically. You need to understand how the binning, review sample and review process in general works.
First off, most reviews are done right after a GPU model releases. Review sites are sent samples of GPUs, which are generally hand picked for bin quality. That usually means they have very efficient, low leakage chips that run a bit cooler and perform a bit better on their stock air coolers.
The cases where info from review sites applies to the consumer is when A), the card is bought near it's release within the same bin lot, or B) only stock speed testing is done or read by the customer. If you wait and buy a card well after the prices drop, there's less chance you'll get the same bin quality.
Note as well that clock speed isn't everything. I've seen reviews that show a much higher clock speed attained on one brand/model of card that ended up resulting in slightly less FPS than another brand/model of card on the game they were benched with when OCed, which was BF3.