AMD Phenom 9900 Processor Hands-On

By: James Yu Posted on December 12, 2007

AMD has recently released the Spider platform, the first joint product launch resulting from the company's merger with graphics manufacturer ATI. The Spider platform consists of three new product lines: the ATI Radeon HD 3800-series GPU, the AMD Phenom CPU, and the AMD 7-series motherboard chipset. This is the first time AMD has been able to offer customers a complete processor, graphics, and motherboard system platform with AMD chips handling all three major functions. They also represent AMD's most advanced technology to date.

The ATI Radeon HD 3800 graphics chips offer more performance and more power efficiency than the Radeon HD 2900 series. The AMD 790 chipset line brings HyperTransport 3.0, PCI Express 2.0, and CrossFireX quad-GPU support to motherboard platforms. GPU updates and new chipsets are always welcome, but the AMD Phenom processor is the most anticipated part of the platform.

AMD earned a lot of credibility in the PC gaming community during the past four years because it was finally able to come up with a CPU design that could take the performance lead away from rival Intel. AMD's Athlon 64 line outperformed the Pentium 4, Intel's best offering at the time. Intel was able to recover the performance lead with its new Core 2 processor line, but AMD had established itself as a viable option among gamers and many looked forward to AMD's new processor, the AMD Phenom.

The AMD Phenom processor features what AMD calls a "true quad-core" design, which has all four processing cores on a single piece of silicon rather than two dual-core processing units side-by-side as Intel does to create its quad-core processors. Having all four processors on a single die allows all the cores on the Phenom chip to share a single L3 cache. Each core still has dedicated L1 and L2 cache, but the shared L3 cache helps improve multicore performance by reducing the amount of time it takes each core to access shared data.

The Phenom features a number of power-saving features designed to increase efficiency. The system can independently adjust the frequency of each core and dynamically disable unused parts of the CPU to reduce power consumption. The Phenom also has several thermal sensors that will automatically reduce the processor speed if heat becomes a problem, in case of CPU fan failure, for example.

The Athlon 64 has an integrated memory controller that helps reduce system memory access time, and AMD has continued supporting that feature in the Phenom by incorporating a DDR2 memory controller on the CPU die. The new integrated memory controller can handle DDR2 memory speeds, ranging from DDR2-400 up to DDR2-1066. AMD has also added HyperTransport 3.0 I/O data bus support, which greatly increases the amount of bandwidth available for data communications, provided that the processor is installed on an HT 3.0 capable motherboard. However, that does not mean that the Phenom will require a motherboard upgrade.

The Phenom is a Socket AM2+ chip, but it will work on current Socket AM2 motherboards. The backward compatibility support will allow current Socket AM2 Athlon 64 owners to upgrade to a Phenom processor without having to buy a new motherboard, but they might have to update the motherboard BIOS. Backward compatibility aside, AMD would still like customers to pick up an AMD 7-series motherboard to go along with every Phenom CPU.

The AMD 7-series chipsets all include Socket AM2+, HyperTransport 3.0, and PCI Express 2.0 support. The AMD 7-series includes three different chipsets: the AMD 790FX at the very high end, the AMD 790X at the merely high end, and the AMD 770 at the mainstream. The main difference between the chipsets is primarily the number of video cards each one supports. AMD 790FX motherboards will be able to support up to four video cards in CrossFireX configuration. AMD 790X boards will handle up to two cards, and the AMD 770 will be the chipset for single-card systems.

AMD will supply motherboard manufacturers with an AMD OverDrive utility that will let users tweak settings, such as CPU speeds, memory timings, and voltages. Experienced users will be able to take advantage of the granular options, but the application will also include an automated "Auto Clock" overclocking feature for beginners.

System Setup: Intel Core 2 Q6700, Intel Core 2 Duo E6700, Intel 975XBX2, AMD Phenom 9900, AMD Phenom 9600, ASUS M3A32-MVP Deluxe, 2GB Corsair XMS Memory (1GBx2), 750GB Seagate 7200.10 SATA Hard Disk Drive, Windows XP Professional SP2. Graphics Card: GeForce 8800 GTX, beta Nvidia ForceWare 169.09.
[Update: We listed the Intel Core 2 Q6700 and the Intel Core 2 E6700 incorrectly as the Q6600 and E6600, respectively, in the system setup. We have corrected the mistake and apologize for the error.]

We tested the 2.6GHz quad-core AMD Phenom 9900 against the 2.66GHz quad-core Intel Core 2 Q6700 to see how the two processors compared on a clock-for-clock basis.

The Intel Core 2 Q6700 turned in the better numbers in all of our tests. The Intel chip may have had an extra 60MHz to work with, but that's not nearly enough clock speed to account for the size of the performance gap. We also included the Intel Core 2 E6700 to see if we could spot any performance differences between dual-core and quad-core. The extra cores seemed to help most in the 3DMark06 CPU benchmark, the Valve Particle test, and the Crysis physics test.

The current Phenom chip design has a bug, or erratum as AMD prefers to call it, that may cause the system to hang in rare instances, such as while running in virtualization mode with high utilization across all four cores. All Phenom processors, including the Phenom 9700 and 9900 shipping in mid-to-late Q1 2008, will have revised cores with an erratum fix in place. Motherboard manufacturers will soon release new BIOS updates to resolve the issue in current Phenom processors, but the fix will result in some performance degradation.

AMD stressed to GameSpot that the problem is extremely rare. So rare, in fact, that users will be able to use the AMD OverDrive utility to disable the errata fix to get full performance out of the processor. The Asus motherboard we tested did not have a BIOS fix, but we did not notice any system instability when we benchmarked our Phenom engineering sample using the motherboard's shipping BIOS. Please keep in mind that our test results show the Phenom running at full power without any errata fix limitations.

Judging by the benchmark results, it looks like AMD will need to increase clock speeds or lower the price of the Phenom to stay competitive with Intel, and it looks like AMD is doing a little of both. AMD has told GameSpot that the Phenom 9900 will sell for "below $350" when the chip arrives next spring. In comparison, the Intel Core 2 Q6700 currently retails for just under $550, but we wouldn't be surprised if Intel cuts the price to give the Phenom 9900 a warm welcome. AMD will also ship a 2.4GHz Phenom 9700 at around the same time for "below $300." Consumers can currently find the 2.2GHz Phenom 9500 and 2.3GHz Phenom 9600 in retail for about $250 and $275, respectively.

The AMD Phenom certainly isn't the Lebron James, Intel-killer many had hoped for, but it also isn't a Kwame Brown-like disappointment. The numbers show us that the CPU is competitive. If AMD can increase the clock speeds and keep the price affordable, the Phenom could very well develop into a star.