The release of the Phenom 9500 and 9600 processors was certainly a rocky one, filled with lower-than-expected clock speeds, lackluster performance and the specter of a TLB bug hovering over the whole operation. At the end of the day, a set of 2.2 and 2.3 GHz quad core Phenom CPUs simply count not compete with the best from Intel, and AMD went away to lick their wounds. But the company didn't stay down for long, as the other parts of the Spider platform continued to do well, and AMD is back with a higher-clocked model, the 2.6 GHz Phenom 9900. This processor is not due to be released until early-2008, but our performance preview will give you an idea of what to expect.
The AMD Phenom offers a true quad core architecture, with four individual cores that can communicate internally and share onboard L3 cache. This differs from the Intel quad core design, where Core 2 Quad/Extreme models are actually two Core 2 Duo models on the same processor package. There is nothing inherently better or worse about these two design calls, as overall performance still tells the tale, but Intel's route does offer a faster time to market, while AMD's may take longer, but can yield greater efficiencies and performance across the multiple cores.
The Phenom processors are built on the 65nm SOI process, and include four individual cores, each with its own 64K + 64K of L1 instruction/data cache (512KB total L1 per processor) and 512KB of L2 cache (2MB total L2 cache). Each Phenom also sports 2MB of integrated L3 cache that is shared by each of the four cores. This translates into an approximate transistor count of 450 million and a die size of 285 mm2. The processor package has also been updated slightly, and while the 940-pin AM2+ design offers some enhancements, the Phenom is fully backward-compatible with the AM2 socket. Even the heatsink-fan assembly has remained consistent.
Like the Athlon 64 X2, the Phenom includes an onboard, dual-channel/128-bit DDR2 memory controller, but support has been upgraded to include DDR2-1066 (with future 45nm support for DDR3). The Phenom's memory controller is slightly different, and is actually dual 64-bit controllers, which can provide 128-bit dual-channel access to system memory, or be configured for individual 64-bit read/write channels. AMD also offers enhanced Cool'n'Quiet support that can dynamically change the clock speeds and voltages of each individual core, or even shut down parts of the CPU to save power.
One interesting facet of the Phenom architecture is its memory controller, which now runs at its own fixed clock, rather than using the divisor method employed by the Athlon 64 X2. There were issues with the latter design, as depending on the CPU multiplier, you could be running your DDR2 anywhere from 716 MHz up to 800 MHz. The Phenom no longer has that limitation, and now operates the DDR2 independent of the CPU frequencies, and always at the proper speed. This translates into the HyperTransport speed as well, with a 1.8 GHz HT (3.6 GHz full duplex) for the Phenom 9500 and 9600, and a higher 2.0 GHz HT (4.0 GHz full duplex) for the Phenom 9700 and 9900.
And yes Virginia, there is a TLB erratum present in the current Phenom revision, specifically erratum 298, which deals with a L3 protocol issue that can cause a system hang when running certain client workloads. All processors have errata, and the chances of this actually happening are slim to none, but AMD issued a temporary BIOS fix, and plans to eliminate the problem in the next B3 silicon. Unfortunately, the BIOS fix entails a performance penalty, but AMD is allowing users to choose whether to disable it using the OverDrive application.
AMD has already introduced the Phenom 9500 (2.2 GHz) and 9600 (2.3 GHz) processors, and the upcoming Phenom 9900 will up the clock speed to a full 2.6 GHz. The rest of the base specifications remain consistent with previous Phenom models, but with some exceptions. The higher clock speed results in a higher 140W TDP and 1.3V operating voltage, and the HyperTransport 3.0 speeds jump to a full 2.0 GHz.
AMD also has a 2.4 GHz Phenom 9700 in the works, which will also debut in early-2008. Add in an unlocked Phenom 9600 "Black Edition" that has just been released, and late-2007 and early-2008 looks to be a very active time for AMD. Here is a small chart that should properly differentiate the various Phenom models, their clock speeds and pricing:
