Issues

Before Phenom's release, it was discovered that a bug in the L3 cache in AMD's quad-core processors could cause a system lockup in rare circumstances. Phenom is affected by this bug up to and including stepping B2. There are BIOS and software workarounds to prevent this problem from occurring, although the workarounds typically employed incur a performance penalty of around 10%. This penalty was not accounted for in early pre-release previews of Phenom, so the performance of early Phenoms delivered to customers is expected to be somewhat below the benchmarks in these previews. Updated CPUs with the bug fixed will be named Phenom 9550 and 9650, and are supposed to arrive "mid to late Q1 2008

SOURCE :- WIKI