The second version, Coppermine, or 80526, had an integrated full-speed 256
KiB L2 cache with lower latency and a 256-bit bus, named
Advanced Transfer Cache by Intel, which improved performance significantly over Katmai. Under competitive pressure from
AMD’s
Athlon processor, Intel also re-worked the chip internally, and finally fixed the well known instruction
pipeline stalls. The result was a remarkable 30% increased performance in some applications where these stalls happened.
It was built on a 0.18
μm process. Pentium III Coppermines running at 500, 533, 550, 600, 650, 667, 700, and 733 MHz were first released on
October 25,
1999. From December 1999 to May 2000, Intel released Pentium IIIs running at speeds of 750, 800, 850, 866, 900, 933 and 1000 MHz (1 GHz). Both 100 MHz FSB and 133 MHz FSB models were made. An "E" was appended to the model name to indicate cores using the new 0.18 μm fabrication process. An additional "B" was later appended to designate 133 MHz FSB models, resulting in an "EB" suffix. In terms of overall performance, the Coppermine held a slight advantage over the Athlons it was released against, which was reversed when AMD applied their own die shrink and added an on-die L2 cache to the Athlon. Athlon held the advantage in floating-point intensive code, while the Coppermine could perform better when SSE optimizations were used, but in practical terms there was little difference in how the two chips performed, clock-for-clock. However, AMD were able to clock the Athlon higher, reaching eventual speeds of 1.4GHz.
A 1.13 GHz version was released in mid-2000 but famously recalled after a collaboration between
HardOCP and
Tom's Hardware discovered various instabilities with the operation of the new CPU speed grade. The Coppermine core was unable to reliably reach the 1.13 GHz speed without various tweaks to the processor's microcode, aggressive cooling, additional voltage (1.75 V vs. 1.65 V), and specifically validated platforms.
[2] Intel only officially supported the processor on its own VC820
i820-based motherboard, but even this motherboard displayed instability in the independent tests of the hardware review sites. In benchmarks that were stable, performance was shown to be sub-par, with the 1.13 GHz CPU equalling a 1.0 GHz model. Tom's Hardware attributed this performance deficit to relaxed tuning of the CPU and motherboard to improve stability.
[3] Intel needed at least six months to resolve the problems using a new cD0 stepping and re-released 1.1 GHz and 1.13 GHz versions in 2001.
Microsoft's
Xbox game console uses a variant of the Pentium III/Mobile Celeron family in a
Micro-PGA2 form factor. The sSpec designator of the chips is SL5Sx, which makes it most similar to the Mobile Celeron
Coppermine-128 processor. It shares with the Coppermine-128 Celeron its 133 MT/s front side bus, 128 KiB L2 cache, and 180 nm fabrication process.
[4]Although the codename Coppermine makes it sound as if the chip was fabricated with
copper interconnects, Coppermine in fact used aluminum interconnects.
In late model Coppermine CPUs, Intel implemented a
integrated heat spreader to improve contact between the die and the
heatsink. The integrated heat spreader itself didn't improve thermal conductivity, since it added another layer of metal and
thermal paste between the die and the heatsink, but it greatly assisted in holding the heatsink flat against the die. Earlier Coppermine CPUs without the integrated heat spreader made heatsink mounting challenging.
[5] If the heatsink was not flat against the die, heat transfer efficiency was crippled. Some heatsink makers also began using pads on their coolers, similar to what AMD did with the "Thunderbird" Athlon. The enthusiast community went so far as to create shims to assist in maintaining a flat interface.
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