The Worst CPUs Ever Made
upstart writes:
Processors are built by multi-billion-dollar corporations using some of the most cutting-edge technologies known to man. But even with all their expertise, investment, and know-how, sometimes these CPU makers drop the ball. Some CPUs have just been poor performers for the money or their generation, while others easily overheated or drew too much power.
Some CPUs were so bad that they set their companies back generations, taking years to recover.
But years on from their release and the fallout, we no longer need to feel let down, disappointed, or ripped off by these lame-duck processors. We can enjoy them for the catastrophic failures they were, and hope the companies involved learned a valuable lesson.
Here are some of the worst CPUs ever made.
Note: Plenty of people will bring up the Pentium FDIV bug here, but the reason we didn't include it is simple: Despite being an enormous marketing failure for Intel and a considerable expense, the actual bug was tiny. It affected no one who wasn't already doing scientific computing, and, in technical terms, the scale and scope of the problem were never estimated to be much of anything. The incident is recalled today more for the disastrous way Intel handled it than for any overarching problem in the Pentium microarchitecture.
Intel Itanium
Intel's Itanium was a radical attempt to push hardware complexity into software optimizations. All the work to determine which instructions to execute in parallel was handled by the compiler before the CPU ran a byte of code.
Analysts predicted that Itanium would conquer the world. It didn't. Compilers were unable to extract necessary performance, and the chip was radically incompatible with everything that had come before it. Once expected to replace x86 entirely and change the world, Itanium limped along for years with a niche market and precious little else.
Itanium's failure was particularly egregious because it represented the death of Intel's entire 64-bit strategy (at the time). Intel had originally planned to move the entire market to IA64 rather than extend x86. AMD's x86-64 (AMD64) proved quite popular, partly because Intel had no luck bringing a competitive Itanium to market. Not many CPUs can claim to have failed so egregiously that they killed their manufacturers' plans for an entire instruction set.
Intel Pentium 4 (Prescott)
Prescott doubled down on the Pentium 4's already-long pipeline, extending it to nearly 40 stages, while Intel simultaneously shrank it down to a 90nm die. This was a mistake.
The new chip was crippled by pipeline stalls that even its new branch prediction unit couldn't prevent, and parasitic leakage drove high power consumption, preventing the chip from hitting the clocks it needed to be successful. Prescott and its dual-core sibling, Smithfield, are the weakest desktop products Intel ever fielded relative to its competition at the time. Intel set revenue records with the chip, but its reputation took a beating.
Its reputation for running rather toasty would be a recurring issue for Intel in the future, too.
AMD Bulldozer
AMD's Bulldozer was supposed to steal a march on Intel by cleverly sharing certain chip capabilities to improve efficiency and reduce die size. AMD wanted a smaller core with higher clocks to offset any penalties from the shared design. What it got was a disaster.
Bulldozer couldn't hit its target clocks, drew too much power, and its performance was a fraction of what it needed to be. It's rare that a CPU is so bad that it nearly kills the company that invented it. Bulldozer nearly did. AMD did penance for Bulldozer by continuing to use it. Despite the core's flaws, it formed the backbone of AMD's CPU family for the next six years.
Fortunately, during the intervening years, AMD went back to the drawing board, and in 2017, Ryzen was born. And the rest is history.
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