Hardware Reference
In-Depth Information
So, of all the chips produced from a single wafer, perhaps more than 75% of them check
out at the highest speed, and only 25% or less run at the lower speeds. The paradox is that
Intel often sells a lot more of the lower-priced, lower-speed chips, so it just dips into the
bin of faster ones, labels them as slower chips, and sells them that way. People began dis-
covering that many of the lower-rated chips actually ran at speeds much higher than they
were rated, and the business of overclocking was born. Similarly, some lower-cost multi-
core processors from AMD have the same physical number of cores as higher-cost ones,
but some cores are disabled during manufacturing.
Processor Re-Marking
Processor remarking, the alterations of chip marking to make a slower chip masquerade
as a faster chip, was once a major problem when virtually all processors could be over-
clocked(runatfasterclockspeedsthannormal).However,withtheadventofretailboxed
processors, clock multiplier locks in most models, and utility programs such as CPU-Z
that can identify processor names andfeatures, processor remarking isnowminimal com-
pared to its heyday over a decade ago.
To make sure your system has the processor you paid for, download and run a copy of
CPU-Z (
http://www.cpuid.com/softwares/cpu-z.html
)
. CPU-Z is the
de facto
standard for
CPU identification and feature display.
PGA Chip Packaging
Variationsonthepingridarray(PGA)chippackaginghavebeenthemostcommonlyused
chippackagesovertheyears.Theywereusedstartingwiththe286processorinthe1980s
and are still used today, although not in all CPU designs. PGA takes its name from the
factthatthechiphasagrid-likearrayofpinsonthebottomofthepackage.PGAchipsare
inserted into sockets, which are often of a zero insertion force (ZIF) design. A ZIF socket
has a lever to allow for easy installation and removal of the chip.
Most original Pentium processors use a variation on the regular PGA called staggered pin
grid array (SPGA), in which the pins are staggered on the underside of the chip rather
than in standard rows and columns. This was done to move the pins closer together and
decrease the overall size of the chip when a large number of pins is required.
Figure 3.6
shows a Pentium Pro that uses the dual-pattern SPGA (on the right) next to a Pentium 66
that uses the regular PGA. Note that the right half of the Pentium Pro shown here has ad-
ditional pins staggered among the other rows and columns.
Figure 3.6
PGA on Pentium 66 (left) and dual-pattern SPGA on Pentium Pro (right).
