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Description:
Overclocking is the
somewhat unknown and uncommon practice of running your CPU (or other
parts) past the speed that it is rated at. An example is running a
200 MHz CPU at 233 MHz. How can this be achieved? The
following description isn't exact, but it captures the basic idea.
Most CPU companies create their CPUs and then test them at a certain
speed. If the CPU fails at a certain speed, then it is sold as a
CPU at the next lower speed. The tests are usually very stringent
so a CPU may be able to run at the higher speed quite reliably. In
fact, the tests are often not used at all. For example, once a
company has been producing a certain CPU for awhile, they have gotten
the process down well enough that all the CPUs they make will run
reliably at the highest speed the CPU is designed for. Thus, just
to fill the demand, they will mark some of them as the slower CPUs.
Beware, however, that some vendors will sell CPUs already overclocked.
This is why it is very important to buy from a dealer you can trust.
TNT and TNT2 video cards are also very overclockable with some companies
like Hercules and Asus selling their cards already overclocked (and
advertised this way). The Hercules drivers and programs like
Powerstrip can often be used on any TNT card to get access to
easy-to-use overclocking utilities.
Also, if you're afraid to overclock your CPU, let another company do it
for you! Companies like ComputerNerd
sells Celeron CPUs pretested at overclocked speeds.
What To
Consider:
- Do
you NEED to overclock? It may not be worth the risk if your
computer is running fine as it is. However, if it seems a
little too slow and/or you're a speed freak, it may be worth the
risk.
- How
important is your work? If you're running a very important
network server, it may not be worth it to put the extra strain on
the computer. Likewise, if your computer does a lot of highly
CPU intensive operations, you may also want to not overclock.
Obviously the most stable computer is going to be one that is not
overclocked. This is not to say that an overclocked computer
can not be 100% stable because they CAN.
Potential
Side-Effects?
- The
first impression people usually have of overclocking is "isn't
that dangerous?" For the most part, the answer is no.
If all you do to try to overclock your computer is change the CPUs
speed, there is almost zero chance that you will damage your
computer and/or the CPU. However, it has happened, but it's a
VERY rare thing. Also, if you start increasing voltage
settings to allow your CPU to run at a higher speed, there is more
of a risk there.
- In
general, as long as you keep your CPU from getting too hot, you
won't have any problems. The only way you can really damage
your CPU is if you don't keep it cool. Adequate cooling is one
of the keys to successful overclocking. Using large heatsinks
with powerful ball-bearing fans will help to achieve this. How
hot is too hot? If you can't keep your finger on the
CPU/heatsink comfortably, then it is probably too hot and you should
lower the CPU's speed.
- Changing
the bus speed is actually more beneficial than changing the CPU's
speed. The bus speed is basically the speed at which the CPU
communicates with the rest of the computer. When you increase
the bus speed, in most cases you will be overclocking all the parts
in your PCI slots and your RAM as well. Usually this is by a
small margin and won't hurt these components. Pay attention to
them though. If they're getting too hot, you may need to add
extra cooling for them (an additional fan in your case). Just
like your CPU, if they get too hot, they may be damaged as well.
Difficulty
Level:
- Believe
it or not, it's actually quite simple. All you have to do is
change a couple of jumpers on the motherboard (in most cases).
Recommendations:
- My
most current recommendation is to get a Celeron 300a CPU and try to
overclock it at 450 MHz. These CPUs are multiplier locked, but
you can change the bus speed. i.e. you can run the 300a at the
following speeds:
- 4.5
* 66 = 300
- 4.5
* 75 = 338
- 4.5
* 83 = 374
- 4.5
* 100 = 450 *the sweet spot*
- 4.5
* 103 = 464
- 4.5
* 112 = 504...
- *Update*
The Celeron 300a is now getting harder to find. The 333 is
also a good overclocker and can be taken to 500 MHz without much
trouble (5x100). The retail versions of these CPUs in the PPGA
format are the best and easiest to overclock, particularly when used
with the most recent MSI Slot1 adapter. Ask
me if you have questions about this...
- However,
it can *not* be run at 4 * 100 for 400 MHz, etc. because only the
4.5 multiplier is supported. On the 333, a 5x multiplier is
supported, the 366 = 5.5, the 400 = 6, and so on.
The current 366 and 400 MHz Celerons are harder to overclock at the
100 MHz bus speed (it's hard to get 550 and 600 MHz out of these
CPUs unfortunately).
- All
you need to do here is use common sense really. For example,
you wouldn't want to try to run a 233 MHz CPU at 400 MHz. For
one thing, it won't work. For another, that probably would
damage your CPU. I would advise starting out low and slowly
trying to go higher. If you have a 233 MHz CPU, try running it
one step higher, then the next step. Most likely you
won't be able to get a CPU like this to run much higher than 300,
but that is a possibility.
- Be
more concerned with changing the bus speed than the CPU speed as
that will provide the greatest amount of speed improvement.
For example, running a CPU at 250 (83.3x3) would be better than
262.5 (75x3.5) in most cases because the bus speed of 83 is higher
than 75. The default for most CPUs is at 66 MHz bus speed.
The newer P2's bus speed is 100 MHz by default. Many computers
will not have options on bus speeds, but if you get any of the motherboards
I recommend, you will have different bus speed options. The
higher bus speed you can run at reliably, the better.
Depending on what your other components are though, they may cause
your computer to crash or become unstable if they can't handle the
higher bus speeds. With bus speeds like 133, you have to have
high quality PC100 SDRAM to be able to achieve this bus speed
reliably.
HOW
to overclock.
If you feel comfortable with this exciting
challenge, read on!
What you'll
need:
An open computer
case and your motherboard manual is all you'll really need to try it,
but more efficient cooling may be useful as well. Of course, your
motherboard needs to support the bus speeds you plan to use and the
multiplier you plan to use. Your motherboard manual should tell
you whether or not it supports certain bus speeds and certain
multipliers. If the exact CPU speed using a particular multiplier
and bus speed isn't listed, don't worry. If you have the proper
multiplier and bus speed in your manual, then you should be okay.
How to
calculate your desired speed:
- First
consider your default speed. For simplicity, lets say it's 300
MHz. If this is a Pentium II processor, it would be running at
the 66.6 MHz bus speed with a multiplier of 4.5 (66.6x4.5 = 300).
- If
you wanted to run at 333, you could increase the multiplier to 5 and
leave the bus speed alone (66.6x5 = 333). *Please note*
today's CPUs (such as the Pentium III) prevent you from changing the
multiplier and only allow you to change the bus speed! The
step below explains how to do this.
- If
you wanted to increase the bus speed and the motherboard supported a
83 MHz bus, you could do something like 83.3x4 for 333 MHz. If
your CPU runs at 100 MHz bus by default, you can try increasing the
bus speed to 112, 124, 133, or other speeds that your motherboard
may support. Calculate your new speed by multiplying it by
your CPU's multiplier.
- If
your motherboard supported the 112 MHz bus speed, you could try 112
bus speed times a multiplier of 3 for 336 MHz.
How to SET this
speed:
- First
thing to consider: Most Pentium II and Celeron CPUs are now
limited to ONE specific multiplier and can only be overclocked by
changing the bus speed! (i.e. 66x4.5 or 100x4.5)
- In
your motherboard manual, find the jumper settings for the particular
bus speed and multiplier you want to use. Locate those jumpers
on your motherboard and change them to fit the jumper settings in
the manual. If it says "closed" for a jumper, then
you need to have the little "shunt" placed over the two
pins for that jumper which "closes" the connection.
If it says "open" you may need to pull off the shunt.
- If
your motherboard has a "SoftMenu," then you can change
your bus speed in the computer's BIOS. Usually you will have
to press F1 or Del to enter your BIOS while your computer is
starting up. Try to locate the CPU speed settings and rotate
through the available bus speeds until you find the one you are
wanting to try.
- That's
all there is to it!
Potential
Solutions...
If the speed you're trying to run at won't work
for some reason, then some of these quick-fix solutions may help...
- Add
additional cooling if your CPU is getting too hot. A fan
blowing on the fan that's on the CPU can help. You could also
try a bigger/better heatsink and fan combo or a Peliter effect
cooler which basically works as a refrigerant for your CPU.
Using thermal grease to seal the connection and enhance heat
transfer between your CPU and heatsink can also be very helpful.
- Though
it can be dangerous if you go too high, you may want to try
increasing the voltage (this isn't very helpful on Pentium II CPUs
above 400 MHz since the limitation on them is the speed of the
cache). Do so in small steps if you can and avoid going more
than four or five tenths of a volt higher. Make sure your CPU
isn't getting too hot as you try this.
Celeron CPUs can usually run reliably at voltages up to 2.3v, but I
would advise not running that high. With Celerons, the
motherboard itself is as important as the CPU in overclocking.
I highly advise the Abit BX6 rev 2 or the BH6 as they both allow
voltage adjustments.
- If
you ARE running a Pentium II past 400 MHz, consider disabling the
chip's cache in your BIOS settings. This effectively makes it
into a Celeron chip, but it can also be changed back. For most
applications, this would be a step backward, but feel free to try it
out.
- If
you're running a Pentium II and it won't let you run at the 100 MHz
bus speed or higher, try to cover up the B21 pin on the CPU. Tom's
Hardware Guide has a good description of this. The same
applies to the Celeron CPUs.
- If
you have an older hard drive ('97 or earlier), consider lowering the
PIO mode in the BIOS as the hard drive may not like the faster bus
speed.
- Adjust
memory timings in your BIOS. Take them as low as you can
without losing stability in an UNoverclocked situation, then try
them in an oveclocked situation.
- If
you run an Athlon CPU, look for a "Golden Fingers" card to
allow you to overclock the CPU.
* If you
have a suggestion, email it to me...
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