Insane. You have to be sick in the head ;)
At that speed is not very stable (it hangs after 10 seconds), but neo565 has been able even to reach 5 Ghz (SD card has burnt). Have more details below...
One thing likes to Overclockers is reach the limit on any device. It's the common goal.
neo565 has managed to be stable 24/7 at 2 GHz. It has used a copper pipe on one end that goes to the CPU. You can see in the next image:
! [overlock] (http://misapuntesde.com/images/2013/08/overclock2.jpg)
This tube has been filled with refrigerant called difluoroethane (LN2) at first. Tests to exceed 3 Ghz has done with tetrafluoroethane (R-134a, used in air conditioners) getting a temperature of approximately -103 degrees Celsius.