Overclocking article in today's WSJ. Celeron 300A mentioned.
John
When Fast Isn't Fast Enough,
There's Always Overclocking
By MIKE ELEK
THE WALL STREET JOURNAL INTERACTIVE EDITION
WHEN MY OLDEST BROTHER, Pat, was 16 years old, he
bought a bright orange 1965 Chevy Malibu. Within a couple of
months, he replaced the chrome grill with a blackout version, added
a tachometer and hood pins, replaced the stock two-barrel
carburetor with a Holley four banger and jacked up the rear end and
fitted it with mag wheels and wide tires.
My mother used to say it was a nice car before he got ahold of it.
She'd probably say the same thing about my computer.
Speed is relative, and within the month it
became obvious that the 333 megahertz
(MHz) my machine was giving me wasn't
going to be enough. Sure, Internet Explorer
and Netscape Communicator snapped
open and Word 97 no longer annoyed me
-- at least after I exorcised the animated
Office Assistant.
But I yearned for power ... computing
power, that is. The solution: overclocking.
In case you haven't heard, overclocking
forces your processor to run faster than its
specifications, and it's the latest rage among hobbyists. For some,
it delivers a modest power boost; for others, a sizable power
increase. One computer magazine even devotes a monthly column
toward this pursuit.
If you decide to go this route, there are a few warnings:
You immediately void your warranty. Of course, if you've built
your own computer, that's not a problem. But think twice
before cracking open the case of your IBM, Gateway, Dell or
Compaq.
Forget about trying to overclock a laptop. Even if you could --
and you probably can't -- it would be perilous for the computer
because of the extra heat that is generated.
Obviously, you have no business altering a computer you use
at work, unless you own the company. This also applies to
leased computers, as well. You don't want to have to explain
overclocking to tech support or the boss -- particularly if you
made a mistake.
I wouldn't try this with a computer that has valuable data on it.
At the very least, back up all of your information. At worst, be
prepared to buy a new computer.
Not everyone will be able to boost their processor. Some
processors simply don't budge from their intended speed.
You get what you paid for -- nothing more, nothing less.
If you're careless or reckless, it is possible to fry your
processor or some of your other costly peripherals. Your hard
drive, memory or video card might begin to act strangely.
Windows itself might not run correctly -- or at all.
The worst-kept secret among hobbyists is that Intel Corp.'s Celeron
processor, specifically the inexpensive Celeron 300A, is a hardy
processor that almost begs to be overclocked. This 300-MHz
processor gets an "A" designation because it adds Level 2 cache
-- high-speed memory that stores recently used information.
The favorite combination is the Celeron 300A, affectionately known
as "the Celery" in overclocking circles, attached to an ABit
Computer Corp. motherboard. So in the interest of knowledge (and
also because of an unfortunate accident -- unrelated to this
experiment -- involving my AsusTek Computer Inc. motherboard), I
picked up both of these items via mail order.
Intel has stopped making the Celeron 300A, but its popularity
persists, and like many things now gone, it has gained a cultlike
following. It's probably the first time that interest in a slower CPU
has actually increased after it was discontinued.
The ABit motherboards are a
good choice for hobbyists,
because they allow nearly all
changes to be made through
software, instead of having to
move jumpers or flip tiny
switches on the motherboard.
Other motherboards also offer
this software-controlled BIOS, although ABit boards seem to be the
most popular.
Overclocking usually involves making two changes: altering the
motherboard's front-side-bus speed or the processor multiplier, or
both. The front side bus, usually known simply as the bus, is the
electronic bridge that allows the processor to communicate with the
rest of the computer's components, such as memory.
The first Pentiums ran with a bus speed of 60 MHz and later 66
MHz -- the speed of the original Pentium processors. As new
processors were introduced, the chip speed became a multiple of
the bus speed. A 90 MHz processor was 1.5 times 60; a 133 MHz
processor was 2 times 66 MHz; 150 was 2.5 times 60; 166 was 2.5
times 66 and so on. Back in those days, you could change the
multiplier and get a small boost in power -- if it worked.
With Intel's release of its Pentium II 350 MHz processors, the bus
speed moved to 100 MHz, and suddenly overclockers had a new
weapon in their quest for processor power.
The multiplier on Intel's newer processors is fixed -- it can't be
changed. The Celeron 300A's multiplier is locked at 4.5 and was
designed to run in a computer with a 66 MHz bus speed -- 4.5 X 66
= 300 MHz (rounded slightly). Overclockers got around that problem
by increasing the bus speed. Many third-party motherboard makers
permit increases in small increments from 66 MHz to 75 MHz to 83
MHz to 100 MHz and beyond.
The one thing that you must consider is how it affects the other
components in your system. Increasing the bus speed also
increases the speed of the PCI slots, which normally run at 33 MHz,
affecting hard drives and video, sound and other peripherals. Some
components are very sensitive to PCI bus speed, while others
seem oblivious.
Getting Along
Here is the relationship between a computer's bus speed, PCI
components and chip speed:
When bus
speed is:
PCI slots
run at:
Celeron 300A
speed is:
(multiplier: 4.5)
Celeron 333
speed is:
(multiplier: 5)
66 MHz
33 MHz
300 MHz
333 MHz
75 MHz
37.5 MHz
338 MHz
375 MHz
83.3 MHz
41.65 MHz
375 MHz
415 MHz
100.2 MHz
33.3 MHz
450 MHz
500 MHz*
103 MHz
33.4 MHz
464 MHz
did not boot
112 MHz
37.3 MHz
504 MHz*
did not boot
* Booted to DOS but wouldn't run Windows.
As the table shows, you're much better off overclocking to a 100
MHz bus speed -- or even 103 MHz -- because the PCI interface
returns to 33 MHz. The 333 MHz processor was unable to reach
that golden 500 MHz speed, but my 300A ran problem-free at 450
MHz -- that's a 50% increase in processing power. That's an
impressive punch for a $75 processor. That in a nutshell explains
the Celeron 300A's popularity.
Others report getting as much as 504 MHz from their Celeron 300A.
But it usually involves disabling many settings, which degrades
system performance. That offsets the advantage of overclocking.
'Juicing the Celery'
Benchmark*
Pentium
200 MHz
Celeron
300 MHz ...
... overclocked
to 450 MHz
CPU Integer
500.4976 MIPS
878.6106 MIPS
1319.047 MIPS
CPU Floating
Point
231.5613
MFLOPS
349.5986
MFLOPS
522.4636
MFLOPS
Memory
183.692 MB/s
522.5173 MB/s
802.8892 MB/s
Cached Disk
33.72919 MB/s
49.15382 MB/s
75.65965 MB/s
MIPS -- million instructions per second
MFLOPS -- million floating-point operations per second
MB/s -- megabytes per second
* Results are from the WinTune 98 benchmark utility from CMP
Media Inc.'s Windows Magazine.
Keeping the processor and motherboard cool is extremely vital:
Heat is the enemy of electronic components. The best way to keep
your system cool is to make sure your power-supply fan is running,
tie down the loose drive and power cables so they don't block air
flow, and add extra cooling fans to your computer.
To cool the processor, there are several Web-based companies
that serve the overclocking market. Some use the tried-and-true
combination of heat sink and fan, while others get more exotic with
Peltier and refrigeration.
I'm using a heat-sink-dual-fan combination from Computer Nerd
(www.dudecomputer.com), which also serves up the
fearsome-looking Wopper Celery Sandwich (two heat sinks and
four fans that wrap around the Celeron processor). While the
computer is running, I can hold my fingers on the heat sink and the
rear of the processor, which means it's running cool. My older
Pentium 200 MMX got so hot running at its rated speed -- even with
a heat sink and fan -- that I couldn't touch the heat sink for more than
a second or two.
Why the difference? Several reasons. One is that the newer
processors use a much thinner slice of silicon, which means they
produce less heat. The other is lower voltage requirements. The
older 486 and Pentium processors used from 5 volts to a split 2.8
or 3.3 volts/5 volts. My Celeron uses just 2 volts, which I bumped up
to 2.1 volts when running at 450 MHz.
Detractors say that overclocking your processor may shorten its life,
as well as affect the surrounding components in your computer.
There's no way of knowing how much time is lopped off a
computer's life expectancy. But all computers' usable lives seem to
be shrinking because of the frequency of newer and faster chips
flooding the market and software that demands those faster chips.
(What became of my Asus P2B and Celeron 333A? I accidentally
erased the BIOS was forced to purchase a replacement BIOS from
Asus. Oops.)
I can't emphasize strongly enough the risks involved in overclocking
any computer. It's a decision -- based on risk vs. performance -- that
each person must make. As for me, I like this newfound speed. I
can only hope that it satisfies my thirst for power ... computing
power, of course.
Very soon, the overclocking argument likely will disappear as Intel
and other chip makers introduce processors that are blazingly fast
and inexpensive, essentially rendering overclocking a hobby of the
past. Still, the Celeron 300A will probably go down in history as the
one of the most popular processors of all time among hobbyists.
Write to Mike Elek at melek@interactive.wsj.com.
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