Advanced Micro Devices is quietly adding DDR-II support into its upcoming Opteron and possibly Athlon 64 microprocessors that are set to come in a pretty near future, sources familiar with the company’s plans revealed.

DDR-II SDRAM support has been a bit tricky for AMD, who integrates memory controller inside its AMD64 central processing units. While DDR-II allows higher memory clock-speeds to be achieved, it also has some drawbacks, such as higher latencies and increased costs initially. Since AMD processors usually work better with lower memory latencies, the company has to carefully consider all the pros and cons of DDR-II support. Generally speaking DDR-II should not only give AMD a higher peak memory bandwidth, but also should compensate its cranked up latencies somehow.

In the fourth quarter of the year AMD is releasing its Winchester and San Diego cores for Athlon 64 and Athlon 64 FX/Opteron CPUs. Both cores are made using 90nm SOI fabrication process and incorporate dual-channel memory controllers. The difference between San Diego and Winchester is in the size of L2 cache – 512KB and 1MB respectively. Sometimes in the early second half of 2005 AMD plans a new 90nm core code-named Toledo for its Opteron and Athlon 64 processors to be released.

Some mainboard makers indicate that there are Opteron processors with dual-channel DDR-II SDRAM memory controllers coming in late Q4 2004 or early Q1 2005. There are no details about the new chips presently, though, this is not the first time, when rumours about DDR-II support by San Diego transpire.

What may seem to be highly possible is that Advanced Micro Devices may add support for 533MHz, 667MHz and 800MHz speed flavours of DDR-II, but not to cope with 400MHz bin. “667MHz may be considered as a good option, keeping in mind its speed, latencies and costs” a source close to the Sunnyvale, California-based chipmaker noted.

Officials for AMD did not comment on the story.