Intel's Pentium II replacement was not yet available but, as a stop-gap, Intel introduced a modestly revised version of the
Pentium II and re-badged it as the "
Pentium III". The base design was unchanged (the addition of
SSE instructions was at that time of no performance significance) but Intel's new production process allowed clockspeed improvements, and it became difficult to determine which company's part was the faster. Both firms were keen to establish a clear lead, and both experienced manufacturing problems with their higher-frequency parts. AMD chose not to sell a 500 MHz or faster K6-III after the rare 500 MHz K6-III had been immediately recalled; it was found to be drawing enough current to damage some motherboards. AMD preferred to concentrate on their soon-to-be-released
Athlon instead. Intel produced a 550 MHz Pentium III with some success but their 600 MHz version had reliability issues and was soon recalled. With the release of the
Athlon, the K6-III became something of an orphan. No longer a competitive CPU in its intended market segment, it nevertheless required substantial manufacturing resources to produce: in spite of its 21.4 million transistors, its 118 mm2 die was considerably smaller than the 184 mm2 of the 22-million-transistor Athlon (cache RAM taking much less area per-transistor than logic), but the K6-III was still significantly more costly to produce than the 81 mm2 9.3 million-transistor K6-2 CPUs (roughly 2/3 the size of the K6-III). For a time, the K6-III was a low priority part for AMD—something to be made only when all orders for high-priced Athlons and cheap-to-produce K6-2s had been filled—and it became difficult to obtain in significant quantities. The original K6-III went out of production when Intel released their "
Coppermine" Pentium III (a much improved part that used an on-die cache) and, at the same time, switched to a new production process. The changeover was fraught with difficulties and Intel CPUs were in global short supply for 12 months or more. This, coupled with the better performance of the Athlon, resulted in even many former Intel-only manufacturers ordering Athlon parts, and stretched AMD's manufacturing facilities to the limit. In consequence, AMD stopped making the K6-III in order to leave more room to manufacture Athlons (and K6-2s).
K6-III+ and K6-2+ By the time the x86 CPU shortage was over, AMD had developed and released revised members of the K6 family. These K6-2+ and K6-III+ variants were specifically designed as low-power mobile (laptop) CPUs, and significantly marked the transition of the K6 architecture (and foretold of AMD's future K7 project) to the new 180 nm production process. Functionally, both parts were die shrunk K6-IIIs (the 2+ disabled 128 KiB of cache, the III+ had the full 256 KiB) and introduced AMD's new
PowerNow! power saving technology. PowerNow! offered processor power savings for mobile applications by measuring computational load, and reduced processor operational voltage and frequency during idle periods in order to reduce overall system power consumption. Although intended for notebook computers, both parts found an enthusiast following also in desktop systems as some motherboard companies (such as Gigabyte and FIC) provided
BIOS updates for their desktop motherboards to allow usage of these processors. For other officially not supported mainboards, the enthusiast community created
unofficial BIOS updates on their own. These boards became firm favorites within the
overclocking community. Both the K6-III+ and K6-2+ 450 MHz CPUs were routinely overclocked to over 600 MHz (). Unfortunately, even with the 180 nm process shrink, the K6 architecture's short 6-stage pipeline while efficient, was difficult to scale with regards to clock speed. K6 III+ and 2+ were never offered higher than 570 MHz officially, and
overclocking efforts using air cooling achieved a maximum around 800 MHz (133x6) at best - however this constraint was also exacerbated by a lack of Socket 7 motherboards supporting stable speeds over 112 MHz
FSB. As AMD's marketing resources at the time were focused on the launch of the upcoming Athlon K7 processor line, the 180 nm K6 series were relatively unknown outside of the industry. == Features ==