How much can I overclock a phenom ii x6 1045t 2.7ghz with stock fan?

^^^^ stock cooler isnt much for anything past default clock speeds. It can be done but many to all will not recommend it. My bro in laws fx 8150 is on the stock cooler and in bf3 gameplay gets in the 55-60 range, but it uses turbo core because i havent touched any settings and it jumps to 4.2Ghz. Also the best for the cost cooler is the cooler master hyper 212 around $25-30, cools as well as most $50+ coolers and recommending an extra fan with the hyper 212 for push/pull