Assuming that you have selected quality components like an excellent motherboard,
high-quality RAM , an excellent thermal solution and an excellent power
supply; you may wonder why your processor won't exceed a certain speed limit.
Lets assume that you have a memory chip that is capable of taking the maximum
frequency the motherboard can throw at it and yet, when you exceed a
certain speed limit you realize that your system becomes unstable.
A PCI bus generally runs at 33 Mhz. When you exceed 35-36 Mhz, the
hard disk and other IDE devices become unstable, because the IDE controller
is controlled through the PCI bus. Oftentimes, you may encounter texture
corruption, when your AGP bus exceeds a certain speed limit. This was often
observed on older motherboards that wouldn’t allow you to lock the AGP and
the PCI bus at stock speeds. The good news: regardless of the FSB speed,
most motherboards nowadays automatically ensure that the frequency of the
PCI, AGP and other buses always remain constant (in other words; their speeds
are locked unless you deliberately change them). This implies that the other
components connected to the motherboard don’t undergo stress when the FSB
speed is raised. You have the fastest RAM you could find and the obscenely
fast speed ratings on your ensure that you can extract the most performance by
bumping up your FSB speed to the limits.
The main culprit that plays the spoilsport is your CPU. Even if you have an
exceptionally good thermal solution, your CPU won’t exceed a certain limit.
Example: I had experimented with a Pentium III 700E Mhz processor and
a Pentium III 800E MHz processor on an Asus CUBX-E motherboard using
Kingston PC-133 SD-RAM. The reason I chose these 2 processors for experimentation
was because they both used a FSB speed of 100MHz. This motherboard
was really flexible, I was able to increment the FSB to 150Mhz. I was
able to extract 1050 MHz from the stock 700Mhz. This is because the multiplier
is 7, which unfortunately cannot be changed. So I bumped up the FSB from
100Mhz to 150 Mhz; which gave me the resultant speed of:
7 (Multiplier) × 150 (FrontSideBus) = 1050MHz (resultantfrequency)
Simple arithmetic? Yes. Now, logically speaking, if I can extract 1050Mhz
from a 700Mhz processor; I should be able to extract 1200Mhz from an 800
MHz processor. This is not true. I tried doing exactly the same with the 800
MHz processor and the Computer crashed. However, it was stable when I set
the FSB speed to 133 MHz. When I set the FSB at 133 MHz ; this was the
result:
8 (Multiplier) × 133 (FrontSideBus) = 1064MHz (resultantfrequency)
This simple experiment shows that a CPU gets saturated after a certain
clock speed. Typical symptoms of an erratic CPU include instability and at
times, you may not be able to boot up at all.
This particular CPU die was manufactured using a 0.18u process. When
Intel launched a similar CPU using a 0.13u process; they shipped those CPUs
with the stock speed of up to 1.4Ghz. This CPU core was based on the P6
Architecture and it used a 10 stage pipeline. Presently, Intel manufactures the
Pentium-M CPU which is based on the P-6 architecture; the difference being
that they manufacture it using a 0.09u process and they have increased the
depth of the pipeline.
These terms may seem cryptic and this concept may be difficult for some
to grasp. It’s really very simple: To be a successful overclocker; you need to
purchase the best CPU possible; not necessarily the fastest. Always go for a
processor that uses the latest manufacturing process. A CPU rated at 3Ghz
which is manufactured by using a 0.13u process won’t overclock as well as a
CPU that is rated at 2.6Ghz using a 0.09u process.
Deeper pipelines ensure that the CPU has the capability to scale higher
in terms of speed. The disadvantage is that a CPU with a deeper pipeline is
slower than a CPU that uses a smaller pipeline assuming that they are running
at the same speed. AMD Athlon CPUs are famous for their relatively short
pipelines. Thats why they perform better than the Pentium 4 CPUs at the
same clock speed. Before purchasing the fastest processor, always keep this in
mind. Choosing a processor smartly helps you extract the maximum speed out
of your machine. You don’t need to know what a pipeline exactly does. Refer
to the processor spec sheet, find out these basic details of the CPU core and its
architecture and choose accordingly.
To increase the computer’s stability, you may also disable the spread spectrum;
set the PCI speed to 100MHz; set the voltage to the middle range, not
too high; and disable any smart fan settings. and those settings works for all
recommended boards.