Overclocking... what are your customers getting
by Alan Zisman
(c) 1999. First
published in Canadian Computer Wholesaler, May 1999
Microcomputers were probably about a week old before
the first users
discovered that it was sometimes possible to trick the CPU into running
faster then the manufacturer intended?overclocking.
While I don?t know of anyone overclocking IBM?s
original PC (using an
Intel 8088 CPU set to a blazing 4.77 MHz), speeding up the 6 MHz 80286
in the next generation IBM AT was pretty common?at least until IBM
the BIOS to refuse to startup at any but the officially designated
In 1990, I bought a 386 CPU and motherboard, second
as a 386-25. Sometime later, I discovered that I?d in fact gotten a
386-16, with the clock crystal replaced to let it run at 24 MHz. (That
machine is still up and running at the faster speed?proof that
need not be a destructive process).
Still, overclocking is illegal?at least if it?s done
at the retail level,
with stores selling, for example, a 300 MHz CPU overclocked to 400 MHz
as a real 400 MHz processor.
But while overclocking can void warranties on
processors, there?s no
law against what a customer does with a product once it leaves the
And in the last year or so, overclocking has become increasingly
at least with some groups of customers.
The boom in overclocking seems to have come about
because of a couple
- game players wanting to squeeze as much
performance as possible
of their systems, while spending as little as possible.
- Intel?s original Celeron, which lacked an L2 cache.
While this made it
a sub-par performer for standard business applications, it made it easy
to overclock, often to spectacular levels.
- A wide price spread between the Celeron and Intel?s
CPU lines: the Pentium II and now III.
Suddenly, many buyers were getting Celeron-266 systems, and hot-rodding
the CPU to speeds close to 400 MHz, resulting in a CPU that performed
a P-II-400 at a fraction of the cost.
With recent steps taken by Intel to limit
overclocking, this fad may
soon die down. For now, you may not choose to overclock your own
and you certainly shouldn?t be selling systems running at higher than
rated speeds. But some of your customers are probably planning to
their systems, and you should know what they?re taking on and what some
of the issues are.
Web sites have sprung up filled with information aimed
Some of the favorites include:
Firing Squad is claiming over 7 million hits per month?an indication of
just how popular overclocking has become.
Overclocking is done by playing with a motherboard?s
and bus speed, in order to send signals to the CPU faster. A stock
300 CPU in a 66 MHz bus would use a 4.5 multiplier, for example.
Leave the multiplier at 4.5 but up the bus speed to 100 MHz, and your
is suddenly running at 450 MHz. (You may have problems with your 66 MHz
RAM doing that, however). Or leave the bus alone, but up the multiplier
to 6.5 and your CPU is running at about 422 MHz, while not stressing
Some tips from the pros:
Once you?ve successfully overclocked a CPU, your system will perform
in some ways, but not necessarily in others.
- Some motherboards make it easier to do this
fiddling. A current
is the Abit BX6 series. While other popular boards, like ASUS?s models
require changing jumper settings for every clock multiplier or bus
alteration, the Abit boards let you do it through software?much nicer.
As well, while some systems force you to choose either 66 or 100 MHz
speeds, Abit (and some others) allow a range of speeds in between.
- Make changes in a series of small steps.
Eventually, you?ll hit a
beyond which you?ll start to see system problems?back up a small step.
- All CPUs are not the same. Even all CPUs of the
same model and speed
are not the same?two seemingly identical Celeron 300s may max out at
speeds, and a few may not allow overclocking at all. A poll on the
site suggests 90% success pushing C-300As to 450 MHz, however.
- Faster CPUs are tending to be less overclock-able,
with reports that
is taking steps to make it more difficult to overclock their newest
433 models. (Sharky Extreme reported disappointment at being unable to
push a C-433 past about 488 MHz, after having pushed a C-366 all the
to 550 MHz). Intel is reported to have locked the clock multiplier on
Celeron models, forcing overclockers to boost the bus speed, which can
cause problems for the rest of the system. In fact, there are early
that Intel has locked the bus speed of its new P-III as well?but given
that CPU?s premium price, this step is more aimed at preventing
abuse than home overclocking.
- The biggest problem with overclocking is the
potential of overheating
CPU. Firing Squad recommends adding thermal paste (a cheap Radio Shack
purchase) between the CPU and the heat sink. Adding fans and heat sinks
is highly recommended, especially in extreme overclocking situations.
consultant, Bill Drake, praises the Global Win fan (Model FAB-24)?a
fan unit. He points out that it?s like having a backup in case one fan
- Be careful upping the CPU voltage (an option with
A small adjustment can increase the speed at which a system can
too big a change can fry the CPU. A Celeron can be boosted from 2 volts
to 2.1 volts, and maybe to 2.2 volts, but that?s about it.
- There is the potential of risk in overclocking. 16%
of the people
to a poll on the System Optimization site reported damaging a CPU or
- CPU benchmarks will improve, but that doesn?t
always mean much in the
- Business applications, for example, won?t show much
if any improvement.
- Even games may not show as much improvement as
hoped for? if Quake is
running at an optimal frame rate, overclocking won?t lead to much
improvement?but you may notice improvements in situations that would
previously stressed your system
- 3D rendering and Adobe Photoshop image editing,
both of which are
CPU intensive, will benefit.