AMD has announced the availability of eight quad-core Opterons, codenamed Barcelona – six months after their formal launch.

It was forced to limit production of Barcelonas shortly after the launch last September because of problems with the Translation Lookaside Buffer (TLB) in the Level 3 cache share by the four cores.

The launch of the company's quad-core Phenom desktop processors was delayed until last week because of a similar problem, which in very rare cases could cause a system to crash.

Untweaked processors have been in limited use and there have been no reports of problems, according to Randy Allen, vice-president of AMD’s server and workstation division.

The Barcelona design is ahead of Intel in that is a true quad-core, not two dual-cores on the same die.

Intel is ahead in offering 45nm-scale miniaturisation; and its Nehalem architecture, due to launch later this year, copies a trick out of AMD's book by bringing the memory controller into the central processor, removing a bottleneck that has given its rival's processors an edge since the launch of the Athlon 64.

AMD has demonstrated 45nm processors but the new chips are all 65nm-scale, clocking 2.0GHz and 2.4GHz; 2.4GHz and 2.5GHZ versions are expected to ship later this year.

Clock rate is no longer a reliable measure of performance as systems vary in how much they do on each pulse. AMD says a Barcelona-powered HP Proliant DL385 G5 has set a new performance record for its class. Barcelonas are said to be also more power efficient than rivals.