As of today, all of AMD’s Barcelona SPEC CPU results so far have just been invalidated and labeled “Not-Available” by SPEC due to violation of the 3-month availability clause. AMD is struggling with availability of its new quad-core “Barcelona” chips because of yield problems in manufacturing and the newly disclosed TLB (Translation Lookaside Buffer) bug. The TLB bug which causes a performance penalty when patched has forced AMD to stop shipping the Opteron chips to all but a few customers and it is impacting AMD financials.
The TLB bug also affects all AMD “Phenom” branded desktop-variant Barcelona processors though AMD is continuing to launch that part because of the rare nature of the problem. Customers will have the option to download the BIOS patch at a later time from their motherboard manufacturer. AMD has confirmed that the fix will come with the next revision called stepping B3 due out in Q1-2008.
Source:→ George Ou's Blog