Today at Computex, AMD took the wraps off of two highly anticipated processors: the Athlon II X2 250 and the Phenom II X2 550 Black Edition. Both are based on AMD's 45nm SOI process with the key difference being the amount of L3 cache. The Phenom II X2 550, codenamed Callisto, gets the full 6 MB cache of the Phenom II family and will serve as AMD's new flagship dual-core processor. The Athlon II X2 250, on the other hand, is based on the new native dual-core Regor die that omits the L3 cache completely and targets the mainstream segment. Benchmark Reviews was fortunate to receive samples of both processors and today we can officially share with you our results. In this review, we focus on the Phenom II X2 550 BE HDZ550WGIBOX.