Again spread via Facebook, we found another overclocking attempt of the upcoming Core i7 4770K Haswell. John Lam and Mad222 from HKEPC shared a video of one of their overclocking attempts. The CPU was briefly clocked at 6.4GHz using 1.445V vCore. This frequency is most likely not very stable since we just see the frequency quickly pop up on CPU-Z and the testing is part of "near voltage and temperature threshold" theory. This same theory was used to clock the Core i7 3770K to 6928MHz with only 1.488V.
In any case, it's an interesting video!