Pentium II Debuts at 300 Mhz: 5/12/97
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VOLUME 11, NUMBER 6 MAY 12, 1997 MICROPROCESSOR REPORT THE INSIDERS’ GUIDE TO MICROPROCESSOR HARDWARE Pentium II Debuts at 300 MHz Better Integer Performance Than All But Fastest Alpha by Linley Gwennap $3,000. At 11.6 SPECint95 (base), the PII-300 will deliver better integer performance than any RISC processor ship- For the first time in 18 months, Intel has introduced a ping today except the 500-MHz 21164, as Figure 1 shows. By new high-end processor, Pentium II (PII), now shipping at the time the 300-MHz chip ships, however, HP and Digital clock speeds of 233 and 266 MHz. In addition, the company plan to offer faster processors. At 6.8 SPECfp95 (base), the plans to ship a 300-MHz version of the chip this summer, PII-300 offers less than half the floating-point performance further boosting its top-of-the-line performance. Even after of most high-end RISC processors. that, Intel won’t sit still for long; a 0.25-micron version of As Intel increases its emphasis on the workstation mar- Pentium II, code-named Deschutes and due around the end ket, it has taken a page from the RISC vendors. Because of the of this year, will reach speeds of at least 400 MHz, according bell-shaped yield curve of CMOS processors, these vendors to the company. have often announced high-end speed grades after skimming Pentium II, formerly known as Klamath (see MPR a handful of the fastest parts off the production line. In the 2/17/97, p. 1), is based on the P6 CPU used in Pentium Pro past, Intel has been loath to follow suit, not announcing parts but adds Intel’s MMX multimedia extensions and features to until it could build them in the volumes required by the PC improve performance on 16-bit code. The chip includes 16K market. This time, by setting a high price, Intel can dampen instruction and data caches, twice the size of Pentium Pro’s PC demand for its fastest speed grade while supplying it in primary caches, but uses a slower bus than Pentium Pro does the smaller quantities needed by workstation makers. This to access the external L2 cache. technique allows Intel to boost its peak performance by about The 233- and 266-MHz parts are aimed at the PC mar- 10% without any design or IC process changes. ket and offer better performance than any other x86 proces- With RISC workstation vendors Digital, HP, and IBM sor. The initial pricing for the parts is high: $775 for the faster part, $636 for the 233-MHz version, both with 512K of Integer 18.3 18.3 cache. But given Intel’s typical rapid price cuts, we expect the 18 17.4 FP price of the 233-MHz part to fall below $500 by the end of 16 15.4 14.5* this year (see MPR 5/12/97, p. 23), making Pentium II attrac- 14 tive to holiday shoppers looking for a premium PC. 12.6 12 11.6* 10.8 Intel will sell Pentium II only on modules that contain 10.7 10.4* 10 the CPU and level-two (L2) cache; the processor will not be 8 available as a standalone chip. The module is functionally 6.8* SPEC95 (base) 5.9 similar to Pentium Pro but uses a PC board instead of a 6 ceramic substrate. Earlier plans for Intel to offer 256K and 4 512K caches have been simplified; the company will offer 2 only the 512K version. 0 Intel Digital HP MIPS Sun IBM Closing the Gap With RISC Pentium II 21164 PA-8000 R10000 Ultra-2 P2SC The 300-MHz chip is intended mainly for workstations and 300 MHz 500 MHz 180 MHz 200 MHz 300 MHz 135 MHz carries a hefty price tag: $1,981. Although this is a record- Figure 1. A 300-MHz Pentium II, with 512K of level-two cache, setting price for an Intel processor, it is well within bounds surpasses the integer score of most RISC processors but falls well for workstation CPUs, which often reach $2,000 or even behind on the floating-point tests. (Source: SPEC except *vendors) 2 PENTIUM II DEBUTS AT 300 MHZ joining Intergraph and Compaq in offering workstations tions, however, the doubling of both the L1 and L2 caches based on Windows NT and P6 processors, we expect the will roughly compensate for the decrease in the bandwidth of market for these x86 workstations to grow considerably over the L2 cache bus. the next few years. With Pentium II at 300 MHz and eventu- For applications that take advantage of Pentium II’s ally faster, Intel can cover the needs of many low-end work- MMX capabilities, the increase will be much more substantial. station users today, the recently disclosed FPU bug (see Based on Intel’s Media Benchmark, the PII-266 delivers 80% www.MDRonline.com/P6/bug for more details) notwith- better performance than a PPro-200, which doesn’t imple- standing. RISC-based systems, however, will still be needed ment MMX, and 38% better performance than a 200–MHz to obtain maximum FP performance. Pentium/MMX (P55C). As Figure 3 shows, however, the increase varies widely, depending on the type of application Half-Speed Cache Has Minimal Impact and how much it takes advantage of MMX. Pentium II nestles snugly at the top of Intel’s product line. This data implies that, for non-MMX applications, a According to the SYSmark tests, the PII-233 is 9% faster than Pentium II would deliver slightly lower performance than a a PPro-200 when running Windows NT applications, while Pentium Pro at the same clock speed and with the same the PII-266 is nearly 20% faster than the PPro-200, as Figure 2 external cache. Although interesting to microarchitects, this shows. Due to the new chip’s 16-bit enhancements, the differ- point is otherwise moot, because Intel has no plans to release ence on Windows 95 is more pronounced; even the PII-233 a version of Pentium II at the same 200-MHz clock speed as outruns the PPro-200 by 19%, while the PII-266 delivers Pentium Pro, nor will it ship versions of Pentium II with less nearly 30% more performance. than 512K of external cache. Most of this performance gain is due to the higher clock speeds. Pentium II also benefits from its 512K L2 cache; the Coexisting With Pentium Pro Pentium Pro was tested with only 256K of cache. (Pentium Although Pentium II would appear to supercede Pentium Pro is available with a 512K cache, but this version is mainly Pro, the two parts will coexist in Intel’s lineup for the rest of used in servers, not PCs, due to its high price.) Pentium II this year. Pentium II is significantly more expensive than loses some performance due to its half-speed L2 cache, but Pentium Pro, which today lists for $407 to $514, and will on these PC applications, the slower cache results in a loss of remain so for most of this year. Pentium Pro will continue to only a few percent of performance. be popular in NT desktop systems and midrange servers, The effect of the slower cache is slightly greater on the while Pentium/MMX serves as the mainstream PC processor SPECfp95 benchmark, where the PII-233 delivers less than throughout 1997. 7% better performance than the PPro-200. This test contains Pentium II has other limitations that will prevent it several programs with large working sets. For most applica- from replacing Pentium Pro in high-end servers. The initial version is limited to single- and dual-processor systems. Although Pentium II, like Pentium Pro, could function prop- 351 350 ■ erly in a four-CPU configuration, Intel feels the 66-MHz P6 315 MMX ● 310 ■ bus doesn’t have enough bandwidth to support the larger 300 NT ● configuration with the faster CPUs. 287 263 ● 255 ★ ■ Whereas the Pentium Pro cache has built-in error cor- 250 ★ 258 223 Win95 237 ● 199 6 200 ★ ★ ■ ● 190 PII-266 5.11 187 179 ★163 5 150 ■ PPro-200 156 Performance ● 100 SYSmark32/NT4.0 4 ★ SYSmark32/Win95 50 ■ Intel Media Benchmark 3 0 2 1.85 1.94 Relative Performance Pentium II Pentium II PPro P55C P54C 1.35 266 MHz 233 MHz 200 MHz 200MHz 200 MHz 1 Figure 2. Even at 233 MHz, Pentium II outperforms Pentium Pro on a variety of benchmarks. Only the Intel Media Benchmark con- tains MMX code. All processors were tested with 512K of burst Audio Video Image 3D SRAM (except Pentium Pro had 256K), 32M of DRAM, a Matrox Millennium graphics card with 2M of WRAM in 1024 x 768 x 256 Figure 3. Individual components of the Intel Media Benchmark mode, and a Seagate ST32550W hard drive. The Pentium systems show a wide variation in the performance advantage of Pentium II used a 430VX chip set and SDRAM; the P6 systems used a 440FX over Pentium Pro. All but the 3D test use MMX. See Figure 2 cap- chip set with EDO DRAM. (Source: Intel) tion for system configurations. (Source: Intel) ©MICRODESIGN RESOURCES MAY 12, 1997 MICROPROCESSOR REPORT 3 PENTIUM II DEBUTS AT 300 MHZ Figure 4. The Pentium II processor module contains a PC-board Figure 5. The PC board is enclosed in a plastic case measuring substrate that holds the Pentium II CPU chip, two L2 data RAMs, 5.73 x 2.47 x 0.66 inches. The case provides physical protection, and various discrete components.