Key Specs
AMD Socket AM2+Four
3GHz
HyperTransport 3.0
2MB
Like the original AMD Phenom, the new 45-nanometer (nm) Phenom II CPU doesn't have the raw speed to dethrone Intel's fastest processor offerings. This inexpensive quad-core processor's performance is competitive in its price range, however, particularly when you consider the low costs of the supporting motherboards and DDR2 memory that it's teamed with. Best of all, the Phenom II doesn't have the heat, power consumption, and errata/performance issues that plagued the original Phenom at launch.
We tested the top-end Phenom II X4 940 Black Edition, a 3GHz CPU with an unlocked clock multiplier that sells for $275. At launch, AMD will also offer the Phenom II X4 920, a 2.8GHz chip with a locked multiplier selling for $235. Both chips fit in AMD's AM2+ socket and will work in existing motherboards, provided the manufacturers supply required BIOS upgrades. We tested using an upgraded MSI DKA790GX Platinum; the Gigabyte MA790GP-DS4H and Asus M3A78-T are also among the early boards to get the necessary BIOS upgrade.
The Phenom II is essentially an optimized version of the original Phenom, with the same basic architecture. The biggest difference is that the 758-million-transistor chip is now based on a smaller 45nm production process, compared to 65nm for the original Phenoms. This results in cooler, lower-power operation and enables both higher clock speeds and more overclocking headroom.
There are performance tweaks throughout the CPU that increase the instructions per cycle that the CPU can execute. All four cores are on a single die, and they share the CPU's built-in memory controller. Each core has 128K of L1 cache and 512K of L2 cache, and there's 6MB of shared L3 cache, up from 2MB of L3 cache for the original Phenom.
For the optimal experience, AMD recommends its "Dragon" platform, consisting of a Phenom II, a 790GX-powered motherboard, and a Radeon 4000-series GPU. With this setup, you can use AMD's Fusion for Gaming and AMD Overdrive utilities to either manually or automatically overclock both the Phenom II and the Radeon in order to maximize performance. With some multiplier and voltage tweaking in AMD Overdrive, we were able to run the Phenom II 940 at 3.6GHz, and determined tweakers could probably squeeze even faster speeds from the chip. With first-generation Phenoms, we were lucky if we could pull off even 10 percent overclocking.
The Phenom II 940 doesn't threaten Intel's new Core i7 CPUs or its even faster Core 2 Quad CPUs in the performance department. However, it's much more competitive than earlier Phenom chips. For instance, in our Sony Vegas MPEG2 rendering test, which utilizes all four cores at full capacity, the original Phenom X4 9850 took 4 minutes and 22 seconds to finish while the Phenom II X4 940 executed the same test in 3 minutes and 43 seconds—exactly the same amount of time it took to run the same test on a Core 2 Extreme QX9770 CPU paired with DDR3 memory. For comparison, Intel's low-end Core i7-920 processor finished the test in just 2 minutes and 50 seconds.
