The new 'Revision E' Athlon 64 cores sport support for DDR500 memory, according to a report at Anandtech
The 'E's sport a good few improvements over the previous stepping of Athlon 64s, including support for SSE3 instructions and a process shrink to 90nm.
However, most interesting is a range of new memory dividers that allow for speeds far higher than the standard 200MHz. For example, an Athlon X2, using the highest divider, can run at 266MHz memory speed, without overclocking either the HyperTransport bus or the processor itself.
As Anand points out, Athlon processors aren't usually very bottlenecked by memory bandwidth - indeed, it's always been one of the strong points of the platform. But with dual-core chips sharing that bandwidth, there is potential for it to become a slow-point, so the support for DDR533 in the X2 is definitely welcome.
AMD has to be very careful about what memory it supports, since the memory controller for the Athlon 64 is on the chip. The upgrade to DDR2 on the AMD side has been long-delayed as AMD waits for the right market conditions. We suspect that even when DDR2 comes further down in price, as it is starting to now, the transition from DDR1 to DDR2 on the AMD side will be a very slow one, as opposed to the incredibly quick change Intel tried to pull. AMD will not want to make customers feel like their DDR1-supporting AMD chip is outdated, as that will make them not best pleased.
Looking forward to DDR2 AMD? Or more happy about breaking out the high-spec DDR on a Rev E? Let us know