The Pentium OverDrive was a microprocessor marketing brand name used by Intel, to cover a variety of consumer upgrade products sold in the mid-1990s. It was originally released for 486 motherboards, and later some Pentium sockets. Intel dropped the brand, as it failed to appeal to corporate buyers, and discouraged new system sales.
The Pentium OverDrive is a heavily modified, 3.3 volt Pentium P54 core manufactured on 0.6 micrometer technology. It is fitted with a 486-compatible bus unit (though with an increased pin-count), an integrated heatsink and fan, and 32 kB of level 1 cache, double the 16 kB offered on regular P54C chips.As the data bus was effectively reduced to 32-bit width, per-clock performance was much lower than that of a 'regular' Pentium, though still substantially faster compared to a similarly-clocked 486 owing to the Pentium's architectural improvements, such as the much improved FPU. It was also equipped with an integrated 3.3 volt power regulator as many 486 motherboards only provided 5 volt power.
The 63 MHz model was launched in February 1995, and supported 25 MHz bus systems. The much faster 83 MHz version, which supported both 25 (63 MHz effective) and 33 MHz bus systems, launched much later the same year on October, and was very expensive at $299 compared to other upgrade alternatives, such as those based on AMD's 5x86 and Cyrix's Cx5x86 chips.
The processor's heatsink is permanently attached, and the removable fan module is powered via spring-like metal prongs that connect to a trio of conductors on the surface of the chip. The clip that releases the fan is visible in the first photo, at the top left corner of the CPU. The central plastic "column" that leads from the center of the fan houses the fan wiring and leads down the side of the heatsink at this corner. The small plastic points at each top left of this column are the locking mechanism for the fan and are released by squeezing them. The opposite corner of the CPU has a latch that locks the fan around underneath the heatsink, by swinging into place upon assembly. The processor monitors the fan and will throttle back on clock speed to prevent overheating and damage if the fan is not operating. This is a predecessor to the internal temperature detection and protection in Intel's modern processors.
During development, Intel had changed the design specification, causing various compatibility and performance problems with some boards that were previously fully compatible. For instance, the Packard Bell 450 motherboard required a specially-designed interposer to be installed between the processor and the motherboard to cope with the changed specification, with the unfortunate consequence of precluding access to the motherboard's level 2 cache, resulting in sub-par performance.In addition, some older chipsets do not support the write-back functionality of the chip's level 1 cache, which could also reduce performance. However, the majority of Socket 3 motherboards, particularly later (post-1994) VLB and most PCI boards, provide proper support for the Pentium OverDrive including fully operational access to the level 2 cache, and many earlier boards also support the processor with varying levels of compatibility and performance.
Performance-wise, many popular synthetic benchmarks of the time showed the Pentium OverDrive under-performing its much cheaper and higher-clocked rivals, though its real-world performance (given the motherboard cache was being optimally used) could be much different: programs that were floating-point dependent or optimized for the Pentium architecture (as were both becoming increasingly common in the mid to late nineties) derived a more substantial benefit from the Pentium OverDrive, particularly the 83 MHz version. In addition, it fully supported programs and operating systems specifically coded for the Pentium architecture, such as many emulators, multimedia utilities and even later Windows operating systems and games; however, the benefit of running such programs on a clock- and motherboard bus-constrained system may be questionable.
Some 63 CPU models (part number 109X4405H6J05) have 234 pins instead of 235. Some CPUs came with the pin chopped off (Pin A4) and others had the pin completely missing and covered with the encapsulation.
Images of 234 pin CPUs
The original Pentium chips ran at higher voltages than later models, with a slower 60 or 66 MHz front side bus speed (Socket 4, 5V). Although little known, Intel did in fact release an OverDrive chip for these sockets, that used an internal clock multiplier of 2, to change them to a "120/133" machine.
The OverDrive Processors for the Pentium 75, 90 and 100 were also released (Socket 5, 3.3 V), running at 125, 150 and 166 MHz (clock multiplier of 2.5). The 125 is an oddity, because Intel never made a Pentium 125 as a stand-alone processor.
These were replaced by Pentium OverDrive MMX, which also upgraded the Pentium 120 - 200 MHz to the faster version with MMX technology.
In 1998 the Pentium II OverDrive, part number PODP66X333, was released as an upgrade path for Pentium Pro owners. This upgrade could be used in single and dual processor Socket 8 systems, or in two sockets of quad processor Socket 8 systems with CPU 3 and 4 removed.
Combining the Pentium II Deschutes core in a flip-chip package with a 512 kB full speed L2 cache chip from the Pentium II Xeon into a Socket 8-compatible module resulted in a 300 or 333 MHz processor that could run on a 60 or 66 MHz front side bus. This combination brought together some of the more attractive aspects of the Pentium II and the Pentium II Xeon: MMX support/improved 16-bit performance and full-speed L2 cache, respectively. The later "Dixon" mobile Pentium II core would emulate this combination with its 256 kB of full-speed cache.
In Intel's "Family/Model/Stepping" scheme, the Pentium II OverDrive CPU is family 6, model 3. Though it was based on the Deschutes core, when queried by the CPUID command, it identified as a Klamath Pentium II.As noted in the Pentium II Processor update documentation from Intel, "although this processor has a CPUID of 163xh, it uses a Pentium II processor CPUID 065xh processor core."
The major customer for the production of these chips was Sandia National Laboratories's ASCI Red supercomputer, which had all 4,510 CPUs upgraded in 1999. After the upgrade the system was once again the world's fastest on the TOP500.
Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices (AMD). The original Athlon was the first seventh-generation x86 processor and was the first desktop processor to reach speeds of one gigahertz (GHz). It made its debut as AMD's high-end processor brand on June 23, 1999. Over the years AMD has used the Athlon name with the 64-bit Athlon 64 architecture, the Athlon II, and Accelerated Processing Unit (APU) chips targeting the Socket AM1 desktop SoC architecture, and Socket AM4 Zen microarchitecture. The modern Zen-based Athlon with a Radeon Graphics processor was introduced in 2019 as AMD's highest-performance entry-level processor.
The Intel 486, officially named i486 and also known as 80486, is a higher-performance follow-up to the Intel 386 microprocessor. The i486 was introduced in 1989 and was the first tightly pipelined x86 design as well as the first x86 chip to use more than a million transistors, due to a large on-chip cache and an integrated floating-point unit. It represents a fourth generation of binary compatible CPUs since the original 8086 of 1978.
IntelDX4 is a clock-tripled i486 microprocessor with 16-kB Level 1 cache. Intel named it DX4 as a consequence of litigation with AMD over trademarks. The product was officially named IntelDX4, but OEMs continued using the i486 naming convention.
The K6 microprocessor was launched by AMD in 1997. The main advantage of this particular microprocessor is that it was designed to fit into existing desktop designs for Pentium-branded CPUs. It was marketed as a product that could perform as well as its Intel Pentium II equivalent but at a significantly lower price. The K6 had a considerable impact on the PC market and presented Intel with serious competition.
The original Pentium microprocessor was introduced by Intel on March 22, 1993. It was instruction set compatible with the 80486 but was a new and very different microarchitecture design. The P5 Pentium was the first superscalar x86 microarchitecture and the world’s first superscalar microprocessor to be in mass production. It included dual integer pipelines, a faster floating-point unit, wider data bus, separate code and data caches as well as many other techniques and features to enhance performance and support security, encryption, and multiprocessing for workstations and servers.
Celeron is Intel's brand name for low-end IA-32 and x86-64 computer microprocessor models targeted at low-cost personal computers.
Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas, as a specialist supplier of math coprocessors for 286 and 386 microprocessors. The company was founded by Tom Brightman and Jerry Rogers. Cyrix founder, president, and CEO Jerry Rogers aggressively recruited engineers and pushed them, eventually assembling a design team of 30 people.
The Pentium II brand refers to Intel's sixth-generation microarchitecture ("P6") and x86-compatible microprocessors introduced on May 7, 1997. Containing 7.5 million transistors, the Pentium II featured an improved version of the first P6-generation core of the Pentium Pro, which contained 5.5 million transistors. However, its L2 cache subsystem was a downgrade when compared to the Pentium Pros.
The Pentium III brand refers to Intel's 32-bit x86 desktop and mobile microprocessors based on the sixth-generation P6 microarchitecture introduced on February 26, 1999. The brand's initial processors were very similar to the earlier Pentium II-branded microprocessors. The most notable differences were the addition of the Streaming SIMD Extensions (SSE) instruction set, and the introduction of a controversial serial number embedded in the chip during manufacturing.
The Pentium Pro is a sixth-generation x86 microprocessor developed and manufactured by Intel and introduced on November 1, 1995. It introduced the P6 microarchitecture and was originally intended to replace the original Pentium in a full range of applications. While the Pentium and Pentium MMX had 3.1 and 4.5 million transistors, respectively, the Pentium Pro contained 5.5 million transistors. Later, it was reduced to a more narrow role as a server and high-end desktop processor and was used in supercomputers like ASCI Red, the first computer to reach the teraFLOPS performance mark. The Pentium Pro was capable of both dual- and quad-processor configurations. It only came in one form factor, the relatively large rectangular Socket 8. The Pentium Pro was succeeded by the Pentium II Xeon in 1998.
The Cyrix 5x86 was a x86 microprocessor designed by Cyrix. Released in August 1995, four months before the more famous Cyrix 6x86, the Cyrix 5x86 was one of the fastest CPUs ever produced for Socket 3 computer systems. With better performance in most applications than an Intel Pentium processor at 75 MHz, the Cyrix Cx5x86 filled a gap by providing a medium-performance processor option for 486 Socket 3 motherboards.
The Am5x86 processor is an x86-compatible CPU introduced in 1995 by AMD for use in 486-class computer systems. It is one of the fastest, and most universally compatible upgrade paths for 486 systems.
A front-side bus (FSB) is a computer communication interface (bus) that was often used in Intel-chip-based computers during the 1990s and 2000s. The EV6 bus served the same function for competing AMD CPUs. Both typically carry data between the central processing unit (CPU) and a memory controller hub, known as the northbridge.
Intel's i486 OverDrive processors are a category of various Intel 80486s that were produced with the designated purpose of being used to upgrade personal computers. The OverDrives typically possessed qualities different from 'standard' i486s with the same speed steppings. Those included built-in voltage regulators, different pin-outs, write-back cache instead of write-through cache, built-in heatsinks, and fanless operation — features that made them more able to work where an ordinary edition of a particular model would not.
The K6-2 is an x86 microprocessor introduced by AMD on May 28, 1998, and available in speeds ranging from 266 to 550 MHz. An enhancement of the original K6, the K6-2 introduced AMD's 3DNow! SIMD instruction set, featured a larger 64 KiB Level 1 cache, and an upgraded system-bus interface called Super Socket 7, which was backward compatible with older Socket 7 motherboards. It was manufactured using a 0.25 micrometre process, ran at 2.2 volts, and had 9.3 million transistors.
The K6-III was an x86 microprocessor line manufactured by AMD that launched on February 22, 1999. The launch consisted of both 400 and 450 MHz models and was based on the preceding K6-2 architecture. Its improved 256 KB on-chip L2 cache gave it significant improvements in system performance over its predecessor the K6-2. The K6-III was the last processor officially released for desktop Socket 7 systems, however later mobile K6-III+ and K6-2+ processors could be run unofficially in certain socket 7 motherboards if an updated BIOS was made available for a given board.
Slot 1 refers to the physical and electrical specification for the connector used by some of Intel's microprocessors, including the Pentium Pro, Celeron, Pentium II and the Pentium III. Both single and dual processor configurations were implemented.
The Intel Core microarchitecture is a multi-core processor microarchitecture unveiled by Intel in Q1 2006. It is based on the Yonah processor design and can be considered an iteration of the P6 microarchitecture introduced in 1995 with Pentium Pro. High power consumption and heat intensity, the resulting inability to effectively increase clock rate, and other shortcomings such as an inefficient pipeline were the primary reasons why Intel abandoned the NetBurst microarchitecture and switched to a different architectural design, delivering high efficiency through a small pipeline rather than high clock rates. The Core microarchitecture initially did not reach the clock rates of the NetBurst microarchitecture, even after moving to 45 nm lithography. However after many generations of successor microarchitectures which used Core as their basis, Intel managed to eventually surpass the clock rates of Netburst with the Devil's Canyon microarchitecture reaching a base frequency of 4 GHz and a maximum tested frequency of 4.4 GHz using 22 nm lithography.
Conroe is the code name for many Intel processors sold as Core 2 Duo, Xeon, Pentium Dual-Core and Celeron. It was the first desktop processor to be based on the Core microarchitecture, replacing the NetBurst microarchitecture based Cedar Mill processor. It has product code 80557, which is shared with Allendale and Conroe-L that are very similar but have a smaller L2 cache. Conroe-L has only one processor core and a new CPUID model. The mobile version of Conroe is Merom, the dual-socket server version is Woodcrest, and the quad-core desktop version is Kentsfield. Conroe was replaced by the 45 nm Wolfdale processor.