AMD K5 microprocessor family

AMD K5 is a Pentium-class 32-bit processor. It was the first x86 processor designed by AMD from the ground up, and not licensed or reverse-engineered as previous generations of x86 processors produced by AMD. Development of K5 microprocessor was announced in June of 1993. The processor was originally planned to be released in 1995 at speeds 100 - 120 MHz, but due to delays attributed to problems with testing and verifying the microprocessor design and compatibility with x86 software, the K5 was released in the March of 1996 at speeds 75 and 90 MHz.

Like other 5th generation x86 processors, the K5 included the following features: superscalar architecture, out of-order speculative execution, branch prediction, 64-bit data bus, integrated FPU, and power-management/SMM modes. Because the integer performance of the K5 was faster than similar clocked Pentium, the processor used Pentium rating (PR) instead of actual frequency to designate its performance. Alas, floating-point performance of the processor was much worse than its Pentium rating.

AMD K5 was produced in speeds up to 200 MHz (200 MHz version was not officially announced by AMD).

Die pictures: AMD K5-PR166ABR
Related Links
Architecture
Identification
Pinouts
Support chips
At a glance
Type:
32-bit CPU
Introduction:
1996
Frequency:
75 - 200 (rated)
AMD K5 75 - AMD-SSA/5-75ABR

75 MHz
296-pin ceramic staggered PGA

AMD K5 PR75 - AMD-K5-PR75ABR

75 MHz
296-pin ceramic staggered PGA

AMD K5 90 - AMD-SSA/5-90ABQ

90 MHz
296-pin ceramic staggered PGA

AMD K5 PR90 - AMD-K5-PR90ABQ

90 MHz
296-pin ceramic staggered PGA

AMD K5 PR100 - AMD-K5-PR100ABQ

100 MHz
296-pin ceramic staggered PGA

AMD K5 PR100 - AMD-K5-PR100ABR

100 MHz
296-pin ceramic staggered PGA

AMD K5 PR120 - AMD-K5-PR120ABQ

120 MHz Rating, 90 MHz Real
296-pin ceramic staggered PGA with gold-plated heatspreader

This is the first K5 processor that internally ran at slower speed than its rated speed. With 90 MHz internal speed, this processor slightly outperformed Pentium 120 in integer applications. Unfortunately, floating point performance of PR120 was significantly slower than the Pentium 120.

AMD K5 PR133 - AMD-K5-PR133ABQ

133 MHz Rating, 100 MHz Real
296-pin ceramic staggered PGA with gold-plated heatspreader

AMD K5 PR133 - AMD-K5-PR133ABR

133 MHz Rating, 100 MHz Real
296-pin ceramic staggered PGA with gold-plated heatspreader

Comparing AMD K5 family with Pentium CPU family you may notice that all AMD K5 microprocessors rated 120 MHz or higher were manufactured with integrated heatspreaders, while the fastest production Pentium microprocessor with integrated heatspreader was Pentium 100. The cause of this is much higher typical power dissipation of AMD K5 microprocessors. For instance, this K5 133 under normal conditions dissipates more than 10 Watt - this is twice as much as typical power dissipation of Pentium 150 microprocessor. Adding copper-based integrated heatspreader to the package helps to spread the heat faster as the copper better conducts the heat then the ceramic.

AMD K5 PR150 - AMD-K5-PR150ABR

150 MHz Rating, 116.7(?) MHz Real
296-pin ceramic staggered PGA with gold-plated heatspreader

This 150 MHz CPU runs at the same bus speed and has the same clock multiplier as K5 133 MHz. Nevertheless, in some tests the processor performs a few percent faster than the K5 133 MHz CPU. This increase in performance was due to changes in the processor core.

150 MHz version of AMD K5 was probably released at the same time as 166 MHz version, but it's difficult to tell for sure because this version was never announced by AMD.

AMD K5 PR166 - AMD-K5-PR166ABQ

166 MHz Rating, 116.7 MHz Real
296-pin ceramic staggered PGA with gold-plated heatspreader

Engineering sample

AMD K5 PR166 - AMD-K5-PR166ABR

166 MHz Rating, 116.7 MHz Real
296-pin ceramic staggered PGA with gold-plated heatspreader

AMD K5 PR200 - AMD-K5-PR200ABX

200 MHz Rating, 133 MHz Real
296-pin ceramic staggered PGA with gold-plated heatspreader

K5 200 MHz version was not officially announced by AMD, probably because this processor was released at about the same time as K6 processors. This CPU runs internally at 133 MHz and has integer performance on par with Pentium 200 processor.

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