Hardware Reference
In-Depth Information
by extension, its system or user. You can enable or disable this feature as desired in the BIOS
Setup. The serial number enables the system/user to be identified by company internal networks
and applications. You can use the processor serial number in applications that benefit from
stronger forms of system and user identification, such as the following:
•
Applications using security capabilities
—Managed access to new Internet content and
services; electronic document exchange.
•
Manageability applications
—Asset management; remote system load and configuration.
Although the initial release of Pentium III processors was made in the improved SECC2 packaging,
Intel later switched to the FC-PGA package, which is even less expensive to produce and enables a
more direct attachment of the heatsink to the processor core for better cooling. The FC-PGA version
plugs into Socket 370 but can be used in Slot 1 with a slotkey adapter.
All Pentium III processors have either 512KB or 256KB of L2 cache, which runs at either half-core
or full-core speed. Pentium III Xeon versions have 512KB, 1MB, or 2MB of L2 cache that runs at
full-core speed. The Pentium III Xeon is a more expensive version of the Pentium III designed for
servers and workstations. All PIII processor L2 caches can cache up to 4GB of addressable memory
space and include ECC capability.
Celeron
The Celeron processor is a chameleon, more of a marketing name than the name of an actual chip. In
its first two versions it was originally a P6 with the same processor core as the Pentium II; later it
came with the same core as the PIII, then the P4 and Core 2, while more recent versions are based on
the Core i3 processor core. The Celeron name represents essentially a version of Intel's current
mainstream chip that Intel has repackaged for lower-cost PCs.
In creating the original Celerons, Intel figured that by taking a Pentium II and deleting the separate L2
cache chips mounted inside the processor cartridge (and deleting the cosmetic cover), it could create
a “new” processor that was basically just a slower version of the Pentium II. As such, the first
266MHz and 300MHz Celeron models didn't include L2 cache. Unfortunately, this proved to have far
too great a crippling effect on performance, so starting with the 300A versions, the Celeron received
128KB of on-die full-speed L2 cache, which was actually faster and more advanced than the 512KB
of half-speed cache used in the Pentium II it was based on at the time! In fact, the Celeron was the
first PC processor to receive on-die L2 cache. It wasn't until the Coppermine version of the Pentium
III appeared that on-die L2 cache migrated to Intel's main processors.
Needless to say, this caused a lot of confusion in the marketplace about the Celeron. Considering that
the Celeron started out as a “crippled” Pentium II and then was revised to actually be superior in
some ways to the Pentium II on which it was based (all while selling for less), many didn't know just
where the Celeron stood in terms of performance. Fortunately, the crippling lack of L2 cache existed
only in the earliest Celeron versions; all of those at speeds greater than 300MHz have on-die full-
speed L2 cache.
Since then, the Celeron has been released in many different versions, with each newer one based on
the then-current mainstream processor. The latest Celerons use the same basic 32nm “Sandy Bridge”
core as more expensive Core i-series second-generation processors. The difference is that the
Celeron versions are offered in lower processor and bus clock speeds and with smaller caches, to
justify a lower price point.
