Overclocking... what are your customers getting
into?
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
hacked
the BIOS to refuse to startup at any but the officially designated
speed.
In 1990, I bought a 386 CPU and motherboard, second
hand?advertised
as a 386-25. Sometime later, I discovered that I?d in fact gotten a
first-generation
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
overclocking
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
store.
And in the last year or so, overclocking has become increasingly
popular,
at least with some groups of customers.
The boom in overclocking seems to have come about
because of a couple
of factors:
- game players wanting to squeeze as much
performance as possible
out
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
official
high-performance
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
like
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
system,
and you certainly shouldn?t be selling systems running at higher than
their
rated speeds. But some of your customers are probably planning to
hot-rod
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
at overclockers.
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
CPU multiplier
and bus speed, in order to send signals to the CPU faster. A stock
Celeron
300 CPU in a 66 MHz bus would use a 4.5 multiplier, for example.
(4.5*66=297).
Leave the multiplier at 4.5 but up the bus speed to 100 MHz, and your
CPU
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
out
your RAM.
Some tips from the pros:
- Some motherboards make it easier to do this
fiddling. A current
favorite
is the Abit BX6 series. While other popular boards, like ASUS?s models
require changing jumper settings for every clock multiplier or bus
speed
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
bus
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
threshold,
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
rating
are not the same?two seemingly identical Celeron 300s may max out at
different
speeds, and a few may not allow overclocking at all. A poll on the
Sharky
site suggests 90% success pushing C-300As to 450 MHz, however.
- Faster CPUs are tending to be less overclock-able,
with reports that
Intel
is taking steps to make it more difficult to overclock their newest
Celeron
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
way
to 550 MHz). Intel is reported to have locked the clock multiplier on
recent
Celeron models, forcing overclockers to boost the bus speed, which can
cause problems for the rest of the system. In fact, there are early
reports
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
commercial
abuse than home overclocking.
- The biggest problem with overclocking is the
potential of overheating
the
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.
Vancouver
consultant, Bill Drake, praises the Global Win fan (Model FAB-24)?a
dual
fan unit. He points out that it?s like having a backup in case one fan
stops working.
- Be careful upping the CPU voltage (an option with
the Abit
motherboards).
A small adjustment can increase the speed at which a system can
boot?but
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
responding
to a poll on the System Optimization site reported damaging a CPU or
computer
component.
Once you?ve successfully overclocked a CPU, your system will perform
better
in some ways, but not necessarily in others.
- CPU benchmarks will improve, but that doesn?t
always mean much in the
real
world.
- 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
already
running at an optimal frame rate, overclocking won?t lead to much
visible
improvement?but you may notice improvements in situations that would
have
previously stressed your system
- 3D rendering and Adobe Photoshop image editing,
both of which are
pretty
CPU intensive, will benefit.