Pentium OverDrive
Encyclopedia
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.
) and a larger 32 KB (16 KB + 16 KB) L1 cache, double its P5-platform Pentium peers. Unfortunately the design was plagued with various compatibility problems. Intel changed the specification during development, rendering previously-compatible motherboard designs incompatible. The chip also did not always benefit from the motherboard's cache RAM, resulting in sub-par performance.
When the Pentium OverDrive 83 MHz launched, significantly later than the mere 63 MHz version, it did so at $299, an exorbitant price compared to other upgrade alternatives. The AMD 5x86
and Cyrix Cx5x86
processors were usually faster and were considerably cheaper. Even Intel's own DX4
, based on an older chip architecture, was typically faster. Only on some applications, where floating point
arithmetic was used, could the Pentium OverDrive outperform its predecessors.
Two interesting parts of the Pentium OverDrive for 486 systems are the integrated fan/heatsink combination and the onboard voltage regulation. The processor cooler is permanently attached and the fan is powered by a trio of conductors on the surface of the chip. They power the fan through spring-loaded metal points in the fan assembly, which is removable to allow replacement of the fan if necessary. The clip that releases the fan is viewable in the photo above, 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.
The onboard power regulation circuitry, partly visible near the bottom of the photo, allows the CPU to operate on boards that provide only 5 volts to the CPU. This is necessary because the processor (die) itself operates at 3.3 V like a regular P54C-core Pentium. Late-model 486 motherboards did provide this voltage, because some late-model 486 CPUs like the AMD 5x86
required it, but many boards only provided 5 V power.
PODP5V63
PODP5V83
, 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
, 3.3V), 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 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, "Please note that 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
' 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
.
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
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
Intel 80486
The Intel 80486 microprocessor was a higher performance follow up on the Intel 80386. Introduced in 1989, it 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...
motherboards, and later some Pentium
Pentium compatible processor
A Pentium compatible processor is a 32-bit processor computer chip which supports the instructions in the IA-32 instruction set that were implemented by the Intel P5 Pentium processor family...
sockets. Intel dropped the brand, as it failed to appeal to corporate buyers, and discouraged new system sales.
486 sockets
The Pentium OverDrive was claimed to enable owners of 486 type motherboards to upgrade their machines to Pentium performance, without the cost of having to replace the entire system. The chip was a heavily modified Pentium P54 architecture, made with 0.6 micrometre technology and operating on 3.3 volts, but with a half-wide data bus (32-bit32-bit
The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory....
) and a larger 32 KB (16 KB + 16 KB) L1 cache, double its P5-platform Pentium peers. Unfortunately the design was plagued with various compatibility problems. Intel changed the specification during development, rendering previously-compatible motherboard designs incompatible. The chip also did not always benefit from the motherboard's cache RAM, resulting in sub-par performance.
When the Pentium OverDrive 83 MHz launched, significantly later than the mere 63 MHz version, it did so at $299, an exorbitant price compared to other upgrade alternatives. The AMD 5x86
AMD 5x86
The Am5x86 processor is an x86-compatible CPU introduced in 1995 by AMD for use in 486-class computer systems. It was one of the fastest, and most universally-compatible upgrade paths for users of 486 systems....
and Cyrix Cx5x86
Cyrix Cx5x86
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...
processors were usually faster and were considerably cheaper. Even Intel's own DX4
Intel 80486DX4
The IntelDX4 is a clock-tripled i486 microprocessor with 16 kB L1 cache. Intel named it DX4 as a consequence of litigation with AMD over trademarks...
, based on an older chip architecture, was typically faster. Only on some applications, where floating point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
arithmetic was used, could the Pentium OverDrive outperform its predecessors.
Two interesting parts of the Pentium OverDrive for 486 systems are the integrated fan/heatsink combination and the onboard voltage regulation. The processor cooler is permanently attached and the fan is powered by a trio of conductors on the surface of the chip. They power the fan through spring-loaded metal points in the fan assembly, which is removable to allow replacement of the fan if necessary. The clip that releases the fan is viewable in the photo above, 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.
The onboard power regulation circuitry, partly visible near the bottom of the photo, allows the CPU to operate on boards that provide only 5 volts to the CPU. This is necessary because the processor (die) itself operates at 3.3 V like a regular P54C-core Pentium. Late-model 486 motherboards did provide this voltage, because some late-model 486 CPUs like the AMD 5x86
AMD 5x86
The Am5x86 processor is an x86-compatible CPU introduced in 1995 by AMD for use in 486-class computer systems. It was one of the fastest, and most universally-compatible upgrade paths for users of 486 systems....
required it, but many boards only provided 5 V power.
PODP5V63
- Introduced February 3, 1995
- 235 pins, P24T pinout
- 5 or 3.3 volts
- L1 Cache 32 KB (16 KB + 16 KB)
- 63 MHz on 25 MHz front side busFront side busA front-side bus is a computer communication interface often used in computers during the 1990s and 2000s.It typically carries data between the central processing unit and a memory controller hub, known as the northbridge....
(25 × 2.5)
PODP5V83
- Introduced October 1995
- 237 pins, P24T pinout
- 5 or 3.3 volts
- L1 Cache 32 KB (16 KB + 16 KB)
- 83 MHz on 33 MHz front side bus (33 × 2.5)
Pentium sockets
The original Pentium chips ran at higher voltages than later models, with a slower 60 or 66 MHz front side bus speed (Socket 4Socket 4
Socket 4, presented in 1993, was the first CPU socket designed for the early P5 Pentium microprocessors. Socket 4 was the only 5-volt socket for the Pentium. After Socket 4, Intel switched to the 3.3-volt-powered Socket 5. Socket 4 does support a special Pentium OverDrive, which allows running at...
, 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.
- PODP5V133: 133 MHz on 66 MHz bus or 120 MHz on 60 MHz bus
The OverDrive Processors for the Pentium 75, 90 and 100 were also released (Socket 5
Socket 5
Socket 5 was created for the second generation of Intel P5 Pentium processors operating at speeds from 75 to 120 MHz as well as certain Pentium OverDrive and Pentium MMX processors with core voltage 3.3 V. Consisting of 320 pins, this was the first socket to use a staggered pin grid array, or...
, 3.3V), 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.
- PODP3V125: 125 MHz on 50 MHz bus
- PODP3V150: 150 MHz on 60 MHz bus
- PODP3V166: 166 MHz on 66 MHz bus
These were replaced by Pentium OverDrive MMX, which also upgraded the Pentium 120 - 200 MHz to the faster with MMX technology.
- BOXPODPMT66X200: up to 200 MHz on 66 MHz bus (clock multiplier of 3.0)
- BOXPODPMT66X166: up to 166 MHz on 66 MHz bus (clock multiplier of 2.5)
- PODPMT60X180: up to 180 MHz on 60 MHz bus (clock multiplier of 3.0)
- PODPMT60X150: up to 150 MHz on 60 MHz bus (clock multiplier of 2.5)
Socket 8
Pentium Pro
The Pentium Pro is a sixth-generation x86 microprocessor developed and manufactured by Intel introduced in November 1, 1995 . It introduced the P6 microarchitecture and was originally intended to replace the original Pentium in a full range of applications...
owners. This upgrade could be used in single and dual processor Socket 8
Socket 8
The Socket 8 CPU socket was used exclusively with the Intel Pentium Pro and Pentium II Overdrive computer processors. Intel discontinued Socket 8 in favor of Slot 1 with the introduction of the Pentium II.-Technical specifications:...
systems, or in two sockets of quad processor Socket 8 systems with CPU 3 and 4 removed.
Combining the Pentium II
Pentium II
The Pentium II brand refers to Intel's sixth-generation microarchitecture 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...
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
CPUID
The CPUID opcode is a processor supplementary instruction for the x86 architecture. It was introduced by Intel in 1993 when it introduced the Pentium and SL-Enhanced 486 processors....
command, it identified as a Klamath Pentium II. As noted in the Pentium II Processor update documentation from Intel, "Please note that although this processor has a CPUID of 163xh, it uses a Pentium II processor CPUID 065xh processor core."
Sandia National Laboratories
The Sandia National Laboratories, managed and operated by the Sandia Corporation , are two major United States Department of Energy research and development national laboratories....
' ASCI Red
ASCI Red
ASCI Red was the first computer built under the Advanced Strategic Computing Initiative . ASCI Red was built by Intel and installed at Sandia in late 1996. The design was based on the Intel Paragon computer...
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
TOP500
The TOP500 project ranks and details the 500 most powerful known computer systems in the world. The project was started in 1993 and publishes an updated list of the supercomputers twice a year...
.
Core specifications
- L1 cache: 16 + 16 KB (Data + Instructions)
- L2 cache: 512 KB external chip on CPU module running at 100% of CPU speed
- Socket: Socket 8Socket 8The Socket 8 CPU socket was used exclusively with the Intel Pentium Pro and Pentium II Overdrive computer processors. Intel discontinued Socket 8 in favor of Slot 1 with the introduction of the Pentium II.-Technical specifications:...
- Front side busFront side busA front-side bus is a computer communication interface often used in computers during the 1990s and 2000s.It typically carries data between the central processing unit and a memory controller hub, known as the northbridge....
: 60 or 66 MHz - VCore: 3.1-3.3 V (Has on-board voltage regulator)
- Fabrication: 0.25 µm
- Based on the Deschutes-generation Pentium II
- First release: 1998
- Supports MMX technology
- The sSpec number SL2KE denotes a Pentium II Overdrive sold with an integrated heatsink/fan combination for Socket 8. [Note that the sSpec number SL2EA denotes a Pentium II Overdrive sold with an integrated heatsink but no fan for Slot 1 and not Socket 8.]