May 31, 2011 20:01 GMT  ·  By

AMD's recently announced delay of the first CPUs built on the high-performance Bulldozer architecture is due to the low clock speeds achieved by these chips, which makes them lag behind Intel's high-end Core i7 processors, according to sources familiar with the company's progress.

The processors are now fully-functional and work without any flaws, but they currently can't operate at high frequencies and cannot achieve the performance levels that AMD anticipated, stated one anonymous source cited by Xbit Labs.

In order to improve the performance of the chips, AMD needs to design a new stepping, that will be referred to as B2.

This will feature the same TDP as the current processors, but is expected to achieve higher clock speeds.

The new stepping should arrive in September, which means that AMD won't start shipping Bulldozer processor until the fourth quarter of 2011, or even early 2012.

Right now, the B0 and B1 revision CPUs built by AMD can function at about 2.5GHz (3.5GHz in Turbo mode) and thus they cannot deliver competitive performance.

The first reports regarding Bulldozer's delay appeared about a week ago, when it was uncovered that motherboard makers had to rely on Bulldozer engineering samples and on older Thuban processors in order to test their AM3+ products, as no retail samples were available from AMD.

These rumors have been confirmed yesterday by the AnandTech publication, which has stated that AMD's Zambezi FX chips will launch in July.

At this year's Computex, AMD was expected to launch four FX-series processors based on the Bulldozer architecture, two featuring eight processing cores while the other two packed six and respectively four CPU cores.

All four chips were targeting the high-end desktop space and were supposed to feature an unlocked multiplier, support for AMD's Turbo Core 2.0 technology and an integrated dual-channel DDR3-1866MHz controller.