Sports fans know that it's not uncommon for a young rookie or draftee to be called a phenom, but it's rare that the label sticks for more than a month or two. Whether it's wilting under pressure, suffering an early-career injury, or finding that once-touted talents simply don't measure up to the pros, the fall of a phenom can be a humbling experience for player and fan alike.

When AMD chose the name Phenom for its new multicore processor, the company was obviously thinking positive, envisioning the CPU as destined for greatness as the Wayne Gretzky or Tiger Woods of desktop technology. Unfortunately, the long-awaited launch of the quad-core Phenom didn't go as planned. Let's take a look at how AMD's trumpet fanfare turned into a dull thud.

A Whole 100MHz Apart

Last week's debut of the Phenom 9000 series starred two quad-core processors -- the 2.2GHz Phenom 9500 and 2.3GHz model 9600. Both utilize 512MB of Level 1 cache (a dedicated 128K per core); 2MB of L2 (a dedicated 512MB per core); and 2MB of shared Level 3 cache (dynamically allocated among the four cores).

The Phenom upgrades the Athlon 64 X2's built-in, dual-channel memory controller with support for DDR-2/1066 and a HyperTransport 3.0 link running at 3.6GHz. Core voltages are between 1.1 and 1.25 volts, bringing both Phenoms in at a thermal design power (TDP) of 95 watts. Prices are lower than expected, as AMD's OEM price list offers the Phenom 9500 and 9600 at $251 and $282, respectively.

AMD is proud to point out that Phenom is a native quad-core design, as opposed to the two-dual-cores-on-one-die strategy that Intel employs with its Core 2 Quad and Extreme CPUs. A native quad-core architecture offers many potential advantages, such as improved intercore communication, faster internal bus speeds, and reduced duplication of resources, all of which can lead to higher performance with lower power and cooling requirements.

But potential advantages don't count on the bottom line -- the real-world power of a chip's core architecture. On a clock-for-clock (throughput at same clock speeds) basis, the Core 2's is a higher-performing architecture than the Phenom's, as well as one that offers significantly more overclocking headroom for enthusiasts and gamers.

This news hit AMD fans like the proverbial glass of cold water in the face. Not only did its lower-than-expected clock speeds keep Phenom from competing at the prestigious high end of the quad-core market, but its clock-for-clock results added insult to injury. Now AMD is forced to position the Phenom 9600 against Intel's lowest-priced quad, the 2.4GHz Core 2 Quad Q6600, while not even equaling it in performance.

Speed Bump Ahead

The biggest letdown of the Phenom launch was the CPU's clock speed. Originally, AMD had promoted 2.6GHz and 2.8GHz Phenoms, while teasing us with visions of a 3.0GHz Phenom FX. But as the months went by, speeds continued to drop. Compared to the prerelease hype, calling the 2.3GHz top of the line a disappointment doesn't begin to say it. AMD pledges to ship 2.4GHz and 2.6GHz parts in the first quarter of 2008 and hit 3.0GHz in the second quarter, but that may be too little too late.

The AMD Phenom was targeted directly against the Intel Core 2. As the dual-core Athlon 64 X2 still offers viable competition in the entry-level and mainstream brackets, many enthusiasts expected Phenom to challenge Intel's high-end Core 2 Quad and Extreme processors. Unfortunately, the absence of any higher-clocked Phenoms immediately took AMD out of the running, forcing the company to cut prices and essentially maintain most of the Athlon 64 X2 versus Core 2 Duo status quo.

In addition, the Phenom is a 65-nanometer-process chip. The 2.2GHz and 2.3GHz models' TDP of 95 watts slips under the 105 watts of Intel's Q6600. But AMD's next baby step upward -- the 2.4GHz Phenom 9700, expected last week but rescheduled for early next year -- jacks this up to 125 watts, an increase of more than 30 percent and well into Core 2 Extreme QX9650 territory. As Intel continues to expand its 45-nanometer-process product offerings, expect the Phenom to look worse and worse in TDP comparisons.

A Ghost in the Machine

With something as detailed as a microprocessor, you can usually expect errata -- glitches or mistakes in the design, some innocuous and some significant. Few become as famous as the floating-point "Pentium bug" of 1997, but every CPU includes errata in one form or another. Serious bugs are usually bandaged with a BIOS update, then officially fixed with a new core revision.

The Phenom 9700 release was delayed by what AMD has listed as Errata 254 -- an issue with the translation look-aside buffer (TLB), a processor cache that handles memory mapping and address translation. The Phenom bug is an L3 cache protocol issue that causes the system to hang when running certain workload applications. It seems most prevalent at 2.4GHz or higher clock speeds; it's been observed at under 2.4GHz, but its effects there are much lower. A processor defect like this might be compared to an unbalanced wheel on your car -- at low speeds it's virtually unnoticeable and at medium speeds a slight irritant, but get that baby on the open highway and your fillings start to loosen.

This errata is not fixed in the current Phenom revision, but there is a BIOS workaround that clears up the TLB issue at the expense of a slight performance loss. The latter suggests an interesting possibility -- that fixing the TLB glitch in Phenom's next hardware stepping might turbocharge overall performance. Add the prospect of 2.4GHz and higher clock speeds, and the Phenom revision could put itself back into contention against the Core 2.

Dark Days and Sleepless Nights

We knew this debut was going to go badly the minute AMD phoned to tell us that the 2.4GHz Phenom 9700 was delayed and that not even the modest Phenom 9500 and 9600 would be shipping en masse to reviewers. When companies operate from a position of strength, their PR campaign is eager to get everyone on the planet to see their products. But when a product launch is underwhelming, phrases like "limiting exposure" come into play and coverage is often scaled back to a bare minimum.

It's amazing how quickly things can change in the PC hardware business. One minute the Athlon 64 X2 is the darling of the performance crowd, and the next, AMD is looking down the barrel of a Core 2 cannon. A reliance on older 65-nanometer technology, a high-profile TLB glitch, and a clock-speed cap of 2.3GHz makes for a very rocky Phenom debut and for headaches and heartburn at AMD.

No other evidence is needed than that, on the same day AMD introduced its 2.2GHz and 2.3GHz Phenoms, Intel cheerfully handed out preview samples of the 3.2GHz Core 2 Extreme QX9770 that'll officially ship in early 2008.