Microsoft is still not saying anything officially about their plans for the successor to the Xbox 360. That hasn't stopped a number of rumors about the console from leaking, however, and the most recent claims involve the next Xbox's processor.

The rumors talk on how AMD is creating the processor for Microsoft.
The CPU inside the console, code named Durango, has two modules, each with four x86 cores inside, according sources sharing these rumors. Each of those cores reportedly runs on a single thread at 1.6Ghz. Also, the cores each feature "a 32 KB instruction cache (I-cache) and a 32 KB data cache (D-cache), and the 4 cores in each module share a 2 MB level 2 (L2) cache. In total, the modules have 8 hardware threads and 4 MB of L2."

The Xbox 720 CPU apparently has a clock speed of 1.6 Ghz, which is actually half the speed of the cores inside the current Xbox 360. The Xbox 360, launched in 2005, has a PowerPC-based processor with three cores and a clock speed of 3.2 Ghz.