So far, we've seen the i7-4770K overclocked to both 7.0 GHz and 8.0 GHz, and now we see another overclocking something that's possibly even more impressive. While the overclock shown here might just be one that goes up to 5.0 GHz, it appears that the overclocker has managed to pull this off at just 0.904 V.
Now, what is clear from the CPU-Z screenshot is that the overclock has been pulled off with HyperThreading disabled.
In the meantime, another overclock was shown as well; one where the chip ran at 3.8 GHz at a mere 0.719 V.
Of course, while these overclocks are impressive, it remains to be seen whether they are actually stable. It is very possible that once a load is applied, the CPU destabilizes and the system crashes.