Advanced Micro Devices needs to improve performance of its FX-series "Zambezi" microprocessors for desktops featuring the Bulldozer micro-architecture before launching them, according to sources with knowledge of the matter. Performance can be improved with a new stepping, which will be production ready only by August.

The long-awaited central processing units (CPUs) featuring the code-named Bulldozer micro-architecture are now fully-functional and work without flaws, according to a person who wished to remain anonymous. The problem with the delay of the AMD FX family of chips is that they currently cannot operate at truly high-speeds and thus cannot achieve performance levels that AMD wanted them to. As result, AMD will need to design a new stepping of the processor and therefore delay the commercial launch to September.

The currently available B0 and B1 stepping Zambezi/Bulldozer processors can function at around 2.50GHz/3.50GHz (nominal/turbo) clock-speeds and at such frequency they cannot deliver performance AMD considers competitive, a person with knowledge of the situation said on Monday. As a consequence, AMD needs to tune the design of the processor and create B2 stepping of the chip with better clock-speed potential amid similar thermal design power (TDP), which will take several months to complete. Therefore, the Sunnyvale, California-based chip designer will release its highly-anticipated Bulldozer processors for desktops in September, not in June, as planned.

Although sales of high-performance microprocessors do not peak in Summer, production ramp usually takes time and therefore launch in September means that the company will only be able to ship "Bulldozers" in high volume sometimes late in 2011 or even in 2012. This will slowdown revenue growth of the chip developer and will also hit its reputation, as this is by far not the first or second delay of Bulldozer in general and Zambezi in particular. AMD itself believed that its multi-core Zambezi FX CPUs will allow it to compete head-to-head with Intel's high-end Core i-series "Sandy Bridge" processors that can sell for as much as $300 and more per chip.

It remains to be seen how the delay of the desktop version of the processor will postpone the release of server versions of the chip with up to sixteen cores. Several high-performance computer makers, including Cray, have already promised to ship supercomputers with the new AMD Opteron "Bulldozer" microprocessors code-named Valencia and Interlagos this year.

AMD did not comment on the story.

Tags: AMD, Zambezi, Bulldozer, 32nm