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Overclocking Guide

Correct Overclocking - The Goals
First and foremost, we want to

* improve overall system performance
* system to be just as stable
* keep our CPU alive!!

The best way to improve system performance is to increase the bus
speed. If you can't do that, either because your motherboard doesn't
support higher bus speeds or your RAM or your PCI devices aren't up to
it, you can change the multiplier instead. Don't expect much gain in
performance, however, if you increase the multiplier but you decrease
the bus speed!!! For example, changing from 166 @ 2.5x66 MHz to 180 @
3x60 MHz will actually decrease your overall performance. The same
rule applies to changing from 133 @ 2x66 to 150 @ 3x50. These types of
changes will not make your system any faster!!

This is some touchy news for 6x86 users, who should really only
overclock their CPUs to a slightly higher speed than the original. The
6x86 only has multiplier options for x2 and x3. Don't let yourself be
told otherwise!! Of course you can try jumpering the board to all of
the different Intel Pentium settings, but it won't make a difference
for the 6x86 CPU.

Overclocking Requirements

Three things are necessary for overclocking:

1. The CPU : HA HA HA !!!

* So far, Intel manufactures the CPUs with the highest quality,
hence the probability of a successful overclocking is highest with
Intel CPUs.
* Check to make sure your Pentium isn't faked. If you can peel off
a black sticker underneath the CPU, it's definitely a re-marked one.
In this case your CPU is most likely already overclocked.

2. The Motherboard

* The quality of the motherboard is crucial for successful
overclocking! Due to the fact that the CPU produces fewer 'clean'
signals in overclocked mode, reflections and other flaws on the bus
can cause the system to crash or hang. The reverse situation is also
true - in overclocked mode the CPU is more sensitive to unstable
signals from the bus and will crash if the motherboard can't deliver
clean signals. Always go for a branded motherboard!
* You will have to decide if you want to go for a higher bus speed
or if you will stick to a maximum of 66 MHz.
* The board should obviously support a wide range of CPU supply
voltages. Minimum are 3.3 and 3.45 V, for STD and VRE voltage. If you
want to use P55C, M2 (the new M1/6x86), or the new K5/K6 CPUs, you
will need support for 'split voltage'. This means that the core of the
CPU requires a lower supply voltage than the I/O ports of the CPU. The
latest boards all support 2.5 up to 2.9 V in 0.1 Volt steps. If the
board offers you an even higher voltage than 3.45 as well, you should
be happy, because this might be the last trick to get your CPU
successfully overclocked.

3. The RAM

* This topic is new, but it is very important indeed. You will
have to consider decent RAM if you want to run your system at bus
speeds of more than 66 MHz. If you want to run an HX board, such as
the Asus P/I-P55T2P4 at 83 MHz bus speed, you will require high-end
EDO. I've experienced myself, that the marking of the RAM is less
important than it's brand. Be careful, however, that you don't get
second-rate chips from the manufacturers being sold in some stores.
These chips still say Siemens, Micron, or whatever on them, but their
quality won't live up to your expectations. In the case of high bus
speeds always go for SDRAM if you can. SDRAM relieves a lot of the
worries of running at 75 or especially 83 MHz, and runs flawlessly in
any case.

4. The Cooling

* I can't proclaim it often enough, the cooling of the CPU is
extremely important ! If you have been able to boot your system with
an overclocked CPU but it crashes within the first minutes, it's most
likely due to insufficient cooling of your processor. Don't think the
average small heat sinks with their small fans designed for a Pentium
are able to do this job properly! Their job is only to keep a normally
clocked CPU cooler in case you have very hot surroundings (e.g. SCSI
or Video cards, which can get very hot as well). They are not designed
to save your overclocked system from crashes due to overheating. This
doesn't mean you always have to have better cooling. If you've got a
new SSS CPU, using the 0.35m die, it just won't get that hot.
* If your CPU is of the old 0.6m die size type, however, you will
require decent cooling. To accomplish this, you can use heat sinks,
fans, or both, peltiers, or peltiers with fans. Peltiers are elements
which transport heat using an electrochemical method from one side of
the element to the other, consuming energy. You will still need a heat
sink to dissipate the heat from the non-CPU side of the peltier and
most likely will also require a fan.
* My opinion is that you should go for a heat sink, and most
importantly THINK BIG !! If a big heat sink still can't do the job,
add a fan on top of it. If you achieve this cooling effect, you can be
sure that any crashes which do occur are not a result of overheating.
So how to get a decent heat sink ? Don't even think of finding
anything in a normal computer shop. You'll find professional heat
sinks only in professional shops which sell electronic equipment such
as transistors, resistors, chips, etc. (e.g. Hobby Electronic Stores).
* You can tell how good a heat sink is by looking at the K/W
value. K/W means degree Kelvin per Watt of power dissipation . K/W
tells how hot the heat sink gets per each Watt of heating power of the
device it's meant to cool. If you were able to follow that, you will
understand that the smaller the value, the better the heat sink. If
you can get a heat sink which has a value below 1K/W, you've found a
good one. You'll need to make the surface of the heat sink that will
attach to the top of the CPU match the size of your CPU (maybe the
electronic shop will cut it for you, otherwise you'll have to do some
sawing and grinding). Be careful that this surface stays completely
flat, so that there are no gaps between the heat sink and the CPU
surface. Finally, you only need to affix the heat sink to the CPU
which is best done with some thermal compound (also available in every
electronic shop). You can also use super glue, but it should be
applied very sparingly with just enough to attach the heat sink. Do
realize that you might not be able to remove the CPU from the heat
sink if the super glue is good stuff. If required, attach a good
(powerful + quiet) fan to the top of the heat sink (how, I will leave
this up to your imagination).
* You should also use besides these hardware solutions some
software solutions like Rain , Waterfall or CPU Idle. These utilities
execute halt instruction during the idle priority thread and thus
keeping the CPU cool. I recommend use of Waterfall because of small
footprint, no VXD's, no drain of any system resources and above all
it's free.

More articles about overclocking visit http.www.network.79br.com

Nov 14 '07 #1
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