Phil Storrs PC Hardware book

The Intel OverDrive processor

During early 1993 some System Board manufacturers supplied Pentium upgradable System Boards. Intel announced the Pentium OverDrive processor in 1993 but it took nearly two years to deliver a Pentium OverDrive processor. Some System Boards have been advertised as having a Pentium OverDrive socket fitted but unfortunately some of these were released before Intel had finalised the Pin-out of it's Pentium OverDrive Processor.

To make the situation even more confusing Intel, in an attempt to make up for the delay in the release of the 64 bit +Pentium OverDrive chip, did release a 32 bit OverDrive processor called the 486 OverDrive. Intel produced a range of Overdrive chips in order to supply upgrade paths for most of the 486 hardware. 486 System Boards could have an 486 OverDrive chip fitted so long as they had :-

The type numbers of the common 486 OverDrive processors were:

Clock speed Processor speed Replaces a 486SX Replaces 486DX
20 40 DX20DP50
25 50 DX20DP50 DX20DPR50
33 66 DX20DP66 DX20DPR66

The above chips feature: Internal maths co-processor
Internal clock speed is 2 times the external clock speed

Clock speed Processor speed Replaces a 486SX Replaces 486DX
20 60 DX40DP75
25 75 DX40DP75 DX40DPR75
33 100 DX40DP100 DX40DPR100

The above chips feature: Enhanced on-chip cache
Enhanced internal maths co-processor, Internal clock speed is 3 times the external clock speed

The Pentium OverDrive

The Pentium OverDrive chip requires a 237 or 238 pin PGA processor socket. When the Pentium OverDrive chip finally arrived it was discovered not all the System Boards manufactured with a Pentium OverDrive socket would actually work with the chip.

The Pentium OverDrive chips have a fan built into a heatsink on top of the chip but the 486 OverDrive chips only have the heatsink and do not require a fan on the processor chip.

The Pentium OverDrive chips

Clock speed Processor speed Replaces 486SX Replaces 486DX
20 50 P0DP5V73
25 63 P0DP5V63 P0DP5V63
33 83 P0DP5V83 P0DP5V83
25 63 P0DP5V63 P0DP5V63
33 83 P0DP5V83 P0DP5V83

The features of these processors are, Superscalar Architecture, Enhanced On-Chip Cache
Faster Maths Coprocessor, Internal clock speed is 2.5 times the external clock speed.


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Copyright © Phil. Storr, last updated 7th December 1998