The AMD Phenom family has a very interesting history, and can trace its lineage back to the infamous TLB-bug and a long game of catch-up with powerhouse Intel. Each new Phenom revision brought AMD closer to the Core 2, and the latest Phenom II X4 introduction finally achieved relative parity with the Core 2 Quad. But those were hybrid AM2+ models, and with their latest Phenom revamp, AMD has formally introduced Socket AM3, further segmenting the Phenom II X4 line and taking the bold move of giving triple-core overclocking to the entry-level masses.
The new AM3 processors remain mostly unchanged from the first-generation of Phenom II models, but there are some important differences. These CPUs are still built on a 45nm SOI process and are native multi-core with a shared L3 cache, but many of the specifications of the AM2+ Phenom II X4 have changed. For starters, the Phenom II AM3 processor die sports a dual-mode memory controller that can use either DDR2 or DDR3, depending on the platform. The DDR2 portion is consistent with AM2+ specifications, and new DDR3 memory controller supports dual channel memory, or separate 64-bit channels, with DDR3-1333 being the standard clock speed.
With the Phenom II X4 800 series, AMD has segmented their quad core line into two specific L3 cache sizes. While the L1 and L2 cache remain unchanged at 64K + 64K of L1 instruction/data cache and 512KB of L2 cache per CPU core, the L3 cache has decreased. The Phenom II X4 900 processors include a full 6MB of L3 cache, while the X4 800 models have dropped to 4MB of L3 cache. Strangely, the Phenom II X3 700 series may drop a core's worth of L1 and L2 cache, but these still maintain a full 6MB of L3 cache. The first-generation Phenom II models ran at a 1.8 GHz HyperTransport clock speed, but this has been upgraded to a full 2.0 GHz for all Phenom II AM3 models.
Compatibility is also an interesting question when it comes to Socket AM3. This current wave of Socket AM3 processors will work on existing Socket AM2+ motherboards, but due to pinouts and the lack of a dual-mode DDR3 memory controller, AM2/AM2+ processors will not be compatible with AM3 motherboards. That means current AM2+ motherboard owners will be able to upgrade to AM3 processors, and keep their DDR2 memory intact, while AM3 platform buyers will be able to utilize faster DDR3 memory.
The Phenom II X3 720 Black Edition is the most surprising processor release from AMD today, as not only is this a low-priced triple-core CPU, but it's a fully unlocked Black Edition that is primed for the hardcore overclocker. Sure, AMD did this previously with the Phenom X3 8750 BE, but now we're talking a highly overclockable Phenom II core. The specifications also include a few surprises, and while the Phenom II X3 720 BE and its three cores include only 1.5MB of L2 cache, it still receives the full Phenom II treatment of a 6MB L3 cache.
The Phenom II X3 720 BE is also clocked at 2.8 GHz, tying with the Phenom II X4 920 for the second-fastest processor in the line, while surpassing it with a full 2.0 GHz HyperTransport speed. Power specifications have also dropped, with a 0.850-1.425V voltage range and a 95W TDP. This TDP rating compares to the 125W of both the Phenom II X4 920 and 940.
While the newest triple-core Phenom II was a bit of a revelation, the Phenom II X4 810 is more of a standard release. This is not a fancy Black Edition model, and instead it has a locked multiplier and as such, will not attract the hardware enthusiasts. This quad core model includes the standard 2MB (4 x 512K) of L2 cache, but AMD has dropped the L3 cache from 6MB on the Phenom II X4 900 models to only 4MB for the X4 800 series.
Its 2.6 GHz clock speed fits the AMD model number scheme, and like all AM3 models, the Phenom II X4 810 has a full 2.0 GHz HyperTransport link. It shares the same basic power specifications as the X3 720, with a slightly higher 0.875-1.425V voltage range and the same 95W TDP. This drop in TDP was not that surprising for a triple-core processor, but lowering all of today's Phenom II X4 models to 95W is a nice move.
AMD is also releasing addition Phenom II models, including the Phenom X3 710 (2.6 GHz, 6MB), X4 805 (2.5 GHz, 4MB) and X4 910 (2.6 GHz, 6MB), with the Phenom X4 805 and 910 being OEM tray only parts.