The AMD Phenom product launch has been one of the most disappointing in recent memory. In addition to unveiling CPUs with lower-than-expected clock speeds and performance, AMD has had to deal with a much-publicized translation look-aside buffer (TLB) bug in the processor that's made potential Phenom desktop buyers very edgy -- and potential Opteron server buyers livid, with bulk shipments of the quad-core "Barcelona" chips announced last September pushed back to the first quarter of 2008.

Something had to change, and it has in an unexpected way: A newly leaked AMD roadmap shows the company's old K8 architecture making a comeback, with no fewer than 11 new and replacement members of the Athlon 64 X2 line projected for 2008. Meanwhile, AMD has apparently fixed the TLB erratum -- twice.

2.8 Days Later

The Phenom was expected to put the final nail in the K8's coffin -- to give AMD's product slate a fresh start with Phenom 9000 series quad-core, Phenom 8000 series tri-core, and Athlon 6000 series dual-core processors.

But that changed within a few days of the Phenom introduction. Like zombies rising from the grave -- or, perhaps more accurately, like another remake of Invasion of the Body Snatchers -- new dual-core K8s will silently replace the old, especially the ones near the top of the performance ladder. The motivating force is AMD's move from 90- to 65-nanometer-process engineering, as 65nm "Brisbane" cores replace 90nm "Windsor" processors (while Intel begins its transition from 65 to 45 nanometers).

With two 512K Level 2 caches, Brisbane is not as speedy as Windsor, which boasts two 1MB caches. So AMD must increase clock speeds to achieve the same performance and keep the same model numbers -- as it's already done with the Athlon 64 X2 4800+, which morphed from a 90-nanometer-process, 2x1MB L2 cache CPU running at 2.4GHz to a 65-nanometer, 2x512K chip running at 2.5GHz. You can expect the 2.8GHz Athlon 64 X2 5600+ to be presto-chango'd into a 2.9GHz processor any day now.

This kind of product flexibility is nice to have, and deserves thanks to the compatibility mantra at AMD. Socket AM2/AM2+ are backward- and forward-compatible, allowing AMD to dip into the K8 pool without upsetting any vendors with Phenom motherboards in stock. Imagine Intel trying the same angle, and you'd have a platform revolt.

Lower thermal design power is another nice benefit of 65-nanometer engineering, as a processor like the Athlon 64 X2 5600+ might drop from 89 watts to 65 watts. AMD is also looking to play the power card a bit longer, introducing new 65nm models ranging from 2.1GHz to 2.5GHz, all with a low 45-watt TDP.

Where things get a little strange is the rumor going around that AMD will be discontinuing the 90nm Athlon 64 X2 6000+ and 6400+, currently its highest-performing dual-core processors. Along with lower power and thermal requirements, the primary benefit of a processor die shrink is traditionally to enable higher clock speeds. This suggests that AMD's 65-nanometer process might not be fully ready for prime time, or at least not ready for 3.1GHz or 3.2GHz clock speeds yet.

Of course, faster Athlon 64 X2s could also be seen as lower-priced competitors to Phenom processors, inspiring AMD to put a clock-speed ceiling on the new Brisbane cores, and therefore AMD could have instituted a clock speed threshold with any new 65nm Brisbane. There has been a small prerelease data leak concerning the performance of a dual-core Phenom, i.e., Athlon 6000 series processor, and while the new CPU does outperform the Athlon 64 X2 on a clock-for-clock basis, the gap is not huge. Maybe AMD doesn't want a 3.3GHz or higher Athlon 64 X2 on the market throwing a monkey wrench into its Athlon 6000 dual-core plans.

R.I.P. To TLB

Yes Virginia, there is a TLB bug in the first wave of Phenom processors -- one originally portrayed as the reason the Phenom debuted at a max clock speed of 2.3GHz, though AMD has since said that the "Level 3 cache errors kick in at 2.4GHz" theory is false. The company's first fix was to cook up a BIOS upgrade, which erases the erratum but, according to online reports, cuts performance by up to 10 percent.

Happily, AMD has now updated the processor itself: The latest B3 core revision not only kicks that particular skeleton out of the closet, but could potentially ramp up both clock speeds and performance. The only hitch is that retail shoppers will have to wait till sometime in the first quarter of 2008, when the B3 technology will arrive in new Phenom 9700 (2.4GHz), 9900 (2.6GHz), and tri-core models -- and apparently in refreshed 2.2GHz and 2.3GHz parts, dubbed Phenom 9550 and 9650, respectively.

Obviously, this is going to have an effect on sales -- you can already hear cries of "Just wait for the B3" echoing throughout the hardware forums of the land. It also makes today's Phenom 9500 and 9600 instant pariahs, raising the specter of a potential recall or at least a silent replacement program for unhappy buyers. AMD knows that customer allegiance is waning, and intends to reward fans by offering an unlocked 2.3GHz Phenom, similar to today's Athlon 64 X2 5000+ Black Edition, before the end of 2008.

Quitting the Quad FX

Another recent announcement has rubbed more salt in AMD enthusiasts' wounds, as the company discontinued its Quad FX dual-socket desktop platform. This news did not receive the play it deserved, for it breaks at least one AMD promise: Initially, AMD allayed fears that Quad FX was a mere stopgap solution against Intel's Core 2 Quad CPUs, assuring shoppers that Quad FX would support next-generation quad-core processors for an upgrade to eight-core nirvana. Unfortunately, that's all water under the bridge, as AMD has stated that any potential upgrade path will not include Phenom-based processors.

It appears now as if the initial prognosis was correct -- that Quad FX was a quick-fix response to the Intel quad-core challenge, which not only wasted a ton of R&D, marketing, and technical resources but has now orphaned a bunch of owners in the all-important enthusiast sector. Sadly, it seems a bunch isn't big enough to justify development of a whole new line of processors, especially when AMD has its hands full with the underwhelming Phenom launch and subsequent rewriting of its CPU roadmap. Then again, a promise is a promise.

Even so, now that the infamous TLB bug is being put to rest and AMD's 65-nanometer transition is underway, there's a window of opportunity for the company to make good in 2008. As much as benchmark performance claims the headlines, it is only part of the equation, and quad-core multiprocessing has its own allure.

If AMD can ramp up production of the Phenom B3 core, get 2.6GHz and faster parts into the channel, and keep prices competitive, sales are sure to increase, especially since the Phenom is backward-compatible with existing Socket AM2 platforms. Right now, AMD may be living out a nightmare, but things can only get better.