Pentium OverDrive
From Wikipedia, the free 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.
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[edit] 486 sockets
The Pentium OverDrive was claimed to enable 486 owners 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-bit) and a larger 32 KB L1 cache, double its P5-platform Pentium peers.[1] 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 very subpar performance on many systems.
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.[2] The AMD 5x86 and Cyrix Cx5x86 processors were usually faster and were vastly cheaper. Even Intel's own DX4, based on an older chip architecture, was typically faster. Only on some applications, where floating point math 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 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 if it is not operating to prevent overheating and damage. This is a predecessor to Intel's modern processors which have internal temperature detection and protection.
The onboard power regulation, somewhat viewable in 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 itself operates at 3.3 V like a regular P54C-core Pentium. Late-model 486 motherboards did support this voltage, because some late-model 486 CPUs like the AMD 5x86 required it, but many boards only supported 5 V output.
PODP5V-63
- Introduced February 3, 1995
- 235 pins, P24T pinout
- 5 volts
- 63 MHz on 25 MHz front side bus (25 × 2.5)
PODP5V-83
- Introduced October 1995
- 237 pins, P24T pinout
- 5 volts
- 83 MHz on 33 MHz front side bus (33 × 2.5)
[edit] 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 4, 5 V). 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.
OverDrives 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. A version was produced for Pentium 120 and 133 owners which ran at speeds of 180 and 200 MHz respectively and included MMX technology.
[edit] Pentium Pro sockets
A chip known as the Pentium II OverDrive was released as an upgrade path for Pentium Pro owners. This CPU had a 333 MHz core and 512KB of integrated cache, running at full core speed (unlike the Pentium II cards where the cache ran at half of the core speed). This upgrade could be used in single and dual processor Socket 8 systems.
[edit] See also
[edit] References
- ^ INTEL ANNOUNCES FIRST PENTIUM(TM) OVERDRIVE(TM) PROCESSOR, Press Release, Google Groups, February, 1995.
- ^ Crothers, Brooke. System upgrades: Intel plans OverDrive for Pentium systems. Infoworld, September 11, 1995, Vol. 17, Issue 37.
[edit] External links
- Intel® OverDrive® processors
- Intel Pentium OverDrive
- Pictures of the 83 MHz Pentium Overdrive
- Intel 83 MHz Pentium Overdrive
- Intel Pentium OverDrive support page
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