HotHardware.com posted a review on the AMD Phenom II TWKR Black Edition Processor

Within the enthusiast scene, there exists an elite group of overclockers who push the limits of hardware to the breaking point. With the help of phase change coolers, dry ice, liquid nitrogen and even liquid helium, these enthusiasts achieve the seemingly impossible. In this world, maximum frequencies and world records are the motivation behind the countless hours spent modding and tweaking PC hardware.

AMD recognized the blood, sweat, and tears that extreme overclockers put into their hobby by creating a very special, limited edition processor made specifically for them. The Phenom II X4 TWKR Black Edition processor is a hand-picked CPU that performs above and beyond the normal parameters we're accustomed to seeing from the Phenom II line. Under the extremely low temps supplied by LN2 or LHe cooling, these chips are said to yield monster overclocks. Check it out...

AMD Phenom II TWKR Black Edition Processor Review