you can easily get 3.8GHz with your 920 and your specs. try 4 GHz, but keep an eye on your temps, coz im not really familiar with thermalright coolers, didnt read some reviews.
This is kind of a silly post from the OP. No direspect, but obviously most 920's "can" reach 3.8, but nothing is guaranteed and noone knows if you can become a good oc'er. Perhaps you make a terrible error that hurts your cpu before you reach your goal. Every cpu is different, every person has a different level of oc'ing ability/competence. Asking someone else if "you" and "your" 920 will reach a certain level is silly. The web is filled with info that says 920's regularly reach 3.8. If you read the sticky on oc'ing and have researched it at all you knew the answer before starting this thread anyway.