We now can confirm that AMD Athlon 64 FX processor based on 90nm San Diego core with Socket 939 form-factor will be launched next year, but will not be pin-to-pin compatible with existing mainboards, as The Inquirer told you earlier.

The new Athlon 64 FX microprocessor with dual-channel memory support is not likely to require expensive registered DIMM modules and hence will be more popular among end users. A problem with it is that it will not be compatible with existing Socket 940 mainboards since the design guide for the part will be available only in October. Looks like AMD goes Intel steps and forces some of its customers to play “change your mainboard game” next year.

Small quantities of the AMD Athlon 64 FX “San Diego” microprocessors made using 90nm fabrication technology in either AMD Fab30 in Dresden, Germany, or in IBM’s East Fishkill facility, will be available at the end of the first quarter next year, whereas massive quantities are expected to hit the market in the second quarter. Their core-clocks are very likely to be 2.60GHz or beyond to beat Intel’s Prescott processors at 3.60 – 3.80GHz that also have 1MB of L2 cache.

There is no information about the branding of San Diego code-named chips, but I would expect them to use the same branding method that will be found on this year’s AMD Athlon 64 FX processors with dual-channel memory controllers.