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How to Configure a CPU Correctly» —>

Introduction

For all of you do-it-yourself experts and tuning fans who want to build or upgrade your own PC system we introduce these tables as quick reference. They provide an overview of all relevant processor and chipset features. The most important things to watch out for when installing a new processor or exchanging the CPU are the core voltage and the multipliers. Apart from this, you’ll find important information about the size of the L2 cache, its ratio to the actual processor clock speed and additional items such as the system bus, architecture and micron manufacturing process here. An extensive chipset overview follows the processor overview. This tells you which CPU is supported by which chipset and gives you the most essential details. Every abbreviation is explained for each table and some are explained using figures.

Slot 1 — SEPP/SECC/SECC2 — Celeron, Pentium II, Pentium III

Slot A — Card Module — Athlon

Socket 370 — PPGA, FC-PGA, Celeron, Cyrix III and Pentium III

Socket 7 — CPGA, PPGA — Pentium, Pentium MMX, K5 and K6 Series

Chipsets and Corresponding Processors

* KX133 Chipset: The FSB of current Athlons (K7) should not exceed 100MHz (x2 or Double Data Rate). The clock rate of 133MHz for the memory interface is produced by an addition of FSB and PCI clock.

** beyond ‘official’ specification, AGP divisor is locked at 2/3 of the system bus, i.e. the AGP bus runs at 88.8MHz when the FSB is 133MHz, default would be 66.6MHz Bus System, also referred to as Front Side Bus (FSB)

Packages and Pinning: The differences between FC-PGA, PPGA, CPGA, Slot 1, Slot A, Socket 370 and Socket 7 in illustrations.

Chaos has been the order of the day from the moment that Intel offered its new Pentium III (Coppermine) as FC-PGA and SECC2 variations. If you take a look at the latest retailer lists, you’ll see that in some cases the Pentium III in FC-PGA is mistakenly listed as a ‘Slot 1’ device. That’s definitely wrong. So what should one know? Basically, the CPU manufacturers distinguish between the packaging and the pinning. This is what processors look like in reality.

Here again is a view of the back of the socketed CPUs. Although the dimensions of the socket 7 and socket 370 devices is the same, these processors have different numbers of pins. Socket 7 CPUs have 321 pins, whereas socket 370 devices have 370 pins.

Note that socket 370 CPUs (Celeron and Pentium III FC-PGA devices) have different pin-outs and different operating voltages. Socket 370 devices are therefore not the same as socket 370 devices! More recent mainboards support both CPUs. Older mainboards (up to December 1999) however, can only support the ‘old’ Celeron (up to 533MHz) and can’t be used with the Pentium III FC-PGA or Celerons over 566MHz with Coppermine core. The latter require lower voltages from 1.65V or even 1.50V.

The same applies to Slot 1 and Slot A. Both connections are mechanically identical — hence the label ‘SC242’ in parenthesis — however, they are not electrically compatible. AMD’s Athlon (Slot A) has a totally different bus protocol to the Pentium II and III. In addition, the chipsets for both CPUs are different. An Athlon can be physically fitted into to a slot 1 board, but it will never work there…

Core Voltage and the Manufacturing Process for Athlon Processors

You want to buy an Athlon but you don’t know whether the retailer is trying to offload an old Athlon manufactured using 0.25 micron technology? From the outside, the old 0.25 devices (model 1) and the 0.18 devices (model 2) look identical. You also don’t know which voltage is needed for the device and this can vary between 1.6V and 1.8V according to the clocking frequency.

With the help of the following table you can read the labeling on the top of the Athlon processor to find out.

This figure shows the label again enlarged. The top line is the most important one, the so-called Ordering Part Number (OPN). The lower line is the serial number which is not so important for you. The following table explains the individual lettering and numbers used.

Marking of Pentium II and Pentium III Processors

Intel have a different marking system for their CPUs. Have a look at the top of this Pentium II processor first.

As you see, Intel’s system is easier to understand for a layman. Most important for you is the top line of this marking.

This figure says it all: Internal clock speed, size of L2 cache, frequency of the Front Side Bus and the core voltage of a Pentium II processor.

Comparing a Pentium III to a Pentium II, you can recognize that there is no big difference in the marking at all. The top line with the most important pieces of information is still the same, only the additional manufacturing markings differs slightly.