Hardware Reference
In-Depth Information
Tip
The current speed of a processor might not be its actual rated speed, either because of over-
clocking or because some recent systems reduce processor speed when the system is not
heavilytasked.BothIntelandAMDhavedevelopedsoftwaretoolsthatcanproperlyidentify
the rated speed of a processor.
For newer Intel processors, use the Intel Processor Identification Utility; for older chips, use
the Intel Processor Frequency ID Utility. Both of these are available from www.intel.com/
support/processors/sb/CS-015477.htm .
For AMD processors, use either the AMD CPU Info program or the AMD Clock program.
To find these, visit http://support.amd.com , select Drivers and Downloads, All Processors.
Then search for CPU info and AMD Clock .
One drawback of the Intel and AMD programs is that they only work on their respective
brandsofchips.AnotherexcellentutilitythatworksonbothIntelandAMDprocessorsisthe
CPU-Z program available from www.cpuid.com . I routinely install this program on any sys-
tems I build or service because it provides universal processor (and chipset) identification.
Users who overclock their systems purchase chips rated at lower speeds and essentially
do their own testing to see if they will run at higher speeds. They can also start with the
highest-rated chips and see whether they can run them even faster, but success there is
much more limited. The most successful overclocking is almost always with the lowest-
rated speed of a given design, and those chips are also sold for the lowest price. In other
words, statistically you might be able to find many of the lowest-speed grade chips that
are capable of running at the highest-speed grade (because they are essentially identic-
al during manufacture); however, if you start with the highest-speed grade, you might be
able to increase the speed only a small percentage.
Just remember that a difference exists between the rated speed of a chip and the actual
maximum speed at which it runs. Manufacturers such as Intel and AMD have to be con-
servative when they rate chips, so a chip of a given rating is almost always capable of
running at least some margin of speed faster than the rating—the question is, how much
faster? Unfortunately, the only way to know that is by trying it out—that is, by testing
chips individually.
Unlocking Cores
A variation of overclocking is the unlocking of disabled cores on AMD Phenom II and
Athlon II processors for better performance in single-threaded and multithreaded applic-
ations and when multitasking. As Table 3.24 indicates, many of AMD's X3 and X2
K10-based processors are based on X4 designs that have one or two cores disabled.
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