Advanced Micro Devices has once again changed its plans regarding the launch of higher-performance AMD Phenom microprocessors. Apparently, the higher speed microprocessors will be released commercially in April, 2008, a little earlier than it was generally expected.

AMD Phenom processor models 9550 (2.20GHz), 9650 (2.30GHz) and 9750 (2.40GHz) will be released commercially about eight weeks from now, sometime in April, a source familiar with the world’s second largest x86 chipmaker’s plans said. The new chips will be based on the B3 revision of the processor and will not have any issues with Translation Lookaside Buffer. The destiny of the high-speed AMD Phenom 9950 is unclear at the moment.

After a Translation Lookaside Buffer (TLB)-related erratum was discovered in AMD Phenom microprocessors and AMD had to impose a fix that reduced performance of the CPUs, Advanced Micro Devices announced a new B3 stepping of the chip with bug corrected without performance degradation. Originally the higher-performance AMD Phenom 9700 and 9900 at 2.40GHz and 2.60GHz, respectively, were scheduled to arrive in Q1, but after a series of delays many suspected that the products slipped into late Q2 or even Q3.

Earlier this week it was reported that virtually all AMD Phenom processors based on the B3 stepping are due in May or June with AMD Phenom 9950 at 2.60GHz scheduled to arrive sometime in the third quarter.

AMD crucially needs new microprocessors with decent performance in its lineup since its aging AMD Athlon 64 X2 family of chips cannot demonstrate performance on par with Intel Corp.’s Core 2 microprocessors. Moreover, with the list of Intel Core 2 Quad central processing units with four processing engines getting longer, AMD’s ability to compete decreases since the company’s lineup of microprocessors contains only two quad-core CPUs.

Officials from AMD did not comment on the news-story.