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] (https://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.
Link: [overclock.net](http://www.overclock.net/t/1404207/extreme-cooled-raspberry-pi)
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