Karbosguide.com - Module 3e.06

Intel Xeon for servers

The contents:

Xeon
A product for servers

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Pentium II Xeon

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Intel always had an important market supplying CPU's for servers. The original Pentium Pro was for several years used for this purpose. Xeon is a line of CPUs for use in servers.

On July 26th, 1998 Intel introduced the Pentium II cartridge named Xeon. Aimed at servers and perhaps high-end users.

The Xeon is a Pentium II in a new cartridge fitting into a new connector called Slot Two. The module is twice as tall as the current Pentium II, but there are other important innovations and improvements:

New type L2 cache RAM chips: CSRAM (Custom SRAM), which runs at full CPU speed.

Different L2 cache sizes: 512, 1,024, or 2,048 KB L2 RAM.

Up to 8 GB RAM can be cached.

Up to four or even eight Xeons in one server.

Support for clustered servers.

New chip sets 82440GX and 82450NX.

The new (huge) cartridge fits into a new Slot Two with three layers of edge connectors. The large L2 caches running high speed will use a lot of power, so cooling will be very important. The cartridge is about twice the size of the well known Pentium II.

A server product

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The Xeon chip is for high performance servers. The first top model will hold 2 MB L2 cache on the cartridge, running at full 450 MHz. This chip costs $4,500!

Performance gain from L2 cache at full speed

The L2 cache of the Xeon runs at full CPU clock speed. One could think, that this would have the same performance as the L1 cache. However the interface from L1 to L2 costs some clock ticks in the beginning of each transmission, so there is some latency. But when data is transferred, it runs at full clock speed.

Practical tests only show an increase in the performance of 5-8% comparing Pentium II and Xeon/512 KB, both running at 450 MHz.

Personally, I find the Xeons too expensive. I know companies who have been advised to and bought the modules with 2 MB cache for use in web-servers. Obviously the price does not matter in those cases, and Intel makes a good profit from that. I do not think the performance matches the price.

Tanner

In 1999 the code name “Tanner” chip became known as the Pentium III Xeon.

Later might follow the processor code named "Foster" which should integrate 2 MB of L2 cache in-chip.

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Read about chip sets on the motherboard in module 2d