AMD's new baby is the Phenom II X4 line-up of desktop processors. Like the original Phenoms that came before it, the new Phenom II X4 processors feature a native quad-core design, with a shared L3 cache, and they fit into current AM2+ sockets. There are quite a few changes under the hood, however, that give Phenom II processors a significant edge is power efficiency and performance over their predecessors, and there are more changes to come in the not too distant future.
The most significant change brought forth with the Phenom II X4 is AMD's use of a 45nm fabrication process to manufacture the chips. The transition to 45nm helped reduce power consumption somewhat, but has also allowed AMD to up the L3 cache to 6MB, while simultaneously shrinking the die to 258mm2 (65nm Phenoms are 285mm2). In addition to the 45nm switch, AMD also re-architected the execution cores to offer higher IPC through enhancements to the architecture, brand predictors, and remapping of the cores within the die. According to AMD, the changes made to the cache and execution cores offer up to 5% and 3% performance improvements, respectively, over the original Phenom design.
Also new to the Phenom II X4 series is a DDR2 and DDR3 compatible integrated memory controller. The first batch of Phenom II processors, like the ones we're looking at today, however, will only work with DDR2 memory. Finally, the new Phenom II X4 processors will be offered at higher frequencies than existing models. The Phenom II X4 920 and 940 we'll be showing you here are clocked at 2.8GHz and 3.0GHz, respectively. The 940 also happens to be a "Black Edition" processor, that ships with unlocked multipliers, for easier overclocking.
Speaking of overclocking, AMD has been touting the frequency headroom in these new processors from quite some time. In fact, at a recent event, we saw one overclocked to over 5GHz--a vast improvement over the 65nm Phenoms. We didn't quite get our sample to go that high, but still hit some respectable numbers. More on that on the next page.
As we've already mentioned, the first two Phenom II X4 processors to be introduced will use the same AM2+ packaging as existing Phenom processors. That means these new chips will be compatible with existing DDR2 platforms, after a BIOS update of course. Future Phenom II processors will employ AMD's socket AM3, which will usher in support for DDR3 memory.
We should note, that future AM3-based Phenom II X4 processors will be backwards compatible with AM2 and AM2+ platforms, and work with DDR2 or DDR3 memory types. But these current AM2+ Phenom II X4 processors will not be forward compatible with AM3/DDR3 platforms.