By: Sarju Shah Posted on April 22, 2008

With quad cores out of the way, you'd think that the next logical step would be eight. There's no doubt that the octo cores are on the way, but AMD decided to go back and fill in some product-line gaps with its new Phenom X3 8000 class of processors. Whereas the Phenom X4 9000 series of processors represents AMD's quad-core parts, the Phenom X3 8000 series consists of triple-core CPUs. Three seems like an odd number when most hardware--memory sizes, processor core counts, GPUs--come in even numbers.

The new triple-core processors actually have the same die as the quad-core 9000 series. The problem with complex multicore processors is that sometimes not all of the cores come out perfectly in the manufacturing process. Through a process called binning, AMD runs each CPU through a battery of tests to determine what kind of performance levels it meets. The tests weed out defective CPUs, assign speed grades to working processors, and determine how many cores will be enabled on a CPU. The GPU manufacturers have been binning their chips for years, and Sony uses a similar process on the eight-core Cell architecture found in the PlayStation 3. Remember how the Sony Cell processor uses only seven of its eight processing cores? That extra core provides a margin of error for manufacturing mistakes. Even though the chip has eight cores, Sony requires only seven of them to work. You can get a lot more chips to pass muster if you relax the requirements.

AMD has three triple-core processors in its line-up: the Phenom X3 8750, 8650, and 8450, which have clocks speeds of 2.4GHz, 2.3GHz, and 2.1 GHz, respectively. AMD states that the new Phenom X3s have launch prices of $195, $165, and $145. All of the CPUs share the same base design, and come with 64KB of L1 instruction and data cache, and 512KB of L2 data cache per core as well as a 2MB shared L3 data cache. The chips are pin compatible with existing socket AM2+ 940-pin motherboards, which makes upgrading to the Phenom X3 about as easy as changing a lightbulb. With a max TDP of 95W, the processors won't guzzle down electrons and will probably exist quite happily in small cases with modest cooling solutions.

Triple-core processing does face some growing pains in the Windows environment. Microsoft designed Windows Vista with the expectation that multicore processors would come in powers of two, and both Intel and AMD have followed that convention up until now. The Phenom X3's triple-core architecture shattered that even-core-count assumption, but Microsoft has already released a Windows Vista hotfix to fully employ the third core. As you may remember, the first Phenom CPUs also arrived with a TLB error that caused systems to hang in very rare instances (specifically, while running in virtualization mode with high CPU utilization across all four cores). Most users would never encounter the error, but AMD chose to move forward with a fix that had the unfortunate side effect of drastically reduced performance. AMD cleared up the TLB error in a matter of months, and all current Phenoms, including the Phenom X3, are working with new, updated designs.

System Setup: AMD Phenom X3 8750, AMD Phenom X4 9600, Intel Core 2 E8200, Gigabyte GA-MA78GM-S2H, Asus P5K, 2GB Corsair XMS Memory (1GB x 2), 750GB Seagate 7200.11 SATA Hard Disk Drive, Windows Vista 32-bit. Graphics Card: GeForce 8800 GTX. Graphics Driver: beta Forceware 174.74.

We pit the new Phenom X3 8750 against similarly priced processors from both Intel and AMD. The Phenom X3 8750 processor faces competition from the $185 2.66GHz dual-core Intel Core 2 Duo E8200 and the slightly more expensive 2.3GHz quad-core AMD Phenom 9600 Black Edition. Our Phenom X3 8750 kept pace with the Core 2 Duo E8200 in all of the tests but Crysis. The Phenom X3 8750 actually outperformed the Core 2 Duo E8200 in Lost Planet, given that the game takes advantage of all three cores. The Phenom X3 8750 fared well against the Phenom 9600 Black Edition both with and without the TLB patch.

The Phenom X3 8750 is a good performer, but it's stuck in a hard spot in terms of pricing. At $195, the Phenom X3 8750 sits a scant $40 away from AMD's flagship desktop processor, the $235 2.5GHz quad-core Phenom X4 9850, and $20 away from the $215 Phenom X4 9750. It's hard to argue for the Phenom X3 8750 at its current price point when you can get higher clock speeds and an additional processing core for just a little more money. When all of AMD's Phenom processors sit within $100 of each other, the argument for the middle children gets to be quite difficult.