engineering sample of AMD’s FX-8130P managed to hit a quite mouthwatering 4.63GHz.
The CPU should be AMD’s fastest Bulldozer offering and its eight cores run at 3.8GHz, or up to 4.2GHz with AMD’s Turbo Core 2.0. It has 8MB of L2 cache, 8MB of L3 cache, supports DDR3 1866MHz and is said to have a 125W TDP.
Pushing it to stable 4.63GHz and completing Super Pi required around 1.5V. You can read more here