Buying and Overclocking the Athlon
By
Johan De Gelas
Wednesday, March 15, 2000 6:36 AM EST
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Bought yourself an Athlon CPU, or you do want to know which Athlon is the most overclockable chip before buying one? We at Ace's Hardware will help you make the right decision for your Athlon-based system, and help you to reach the highest, yet stable, possible for your new CPU.
We also review two special overclocking devices, a simple but efficient
design from the German Hardware Labs,
and a sophisticated professional design from PowerChips, the PowerCharger. This is not supposed to be a huge roundup of overclocking devices, but more like a manual of what you need to know about "Athlon overclocking."
If you have a K6-III, you can find a splendid article
here, written by Jasin Robertson. If you still have a Socket 7
chip like a Pentium MMX, Cyrix MII, AMD K6 or K6-2, you can find a lot
of basic info here.
More advanced overclocking information, look here.
The Basics
Overclocking� and technical hotshots may want to skip this part.
I wrote this for the folks who are new to CPU/Athlon overclocking.
Disclaimer: Ace's Hardware cannot be held responsible for any damage incurred by overclocking your CPU. By using this information, you agree not to hold Ace's Hardware liable for any damages to your CPU or system.
The Athlon is one of the best overclockers ever. Thanks to its well
balanced super-pipelined architecture, this chip is built for high clockspeeds.
Combine this with the fact that AMD's process technology has improved vastly over the past few years and you will understand why most Athlon CPUs clock very high. So, how do you overclock an Athlon CPU? There are two ways to overclock
an Athlon:
1) Increase the FSB
Buy yourself a�Slot A motherboard�(best results: ASUS K7M
or ASUS K7V) that enables you to increase the FSB. The FSB, or Front Side
Bus, is the bus between the chipset and the CPU (technical background here), which normally runs at 100 MHz. The CPU derives it speed by multiplying this bus by the configured multiplier. A 750 Mhz CPU uses a 7.5x multiplier, for example.
It doesn't matter whether the motherboard is based on the VIA KX-133, using 133 MHz memory or is based on the AMD 750 chipset, using 100 MHz memory.
The CPU derives its clockspeed from the chipset-CPU bus� (100 MHz
DDR or the equivalent of 200 MHz), not from the memory-chipset bus.
So, if you increase the CPU-chipset bus frequency to, for example, 110 MHz instead of 100 MHz, the processor will run 10% faster. As the FSB is a Double Data Rate bus, it is very sensitive to high clockspeeds. The K7V-RM that came
with our AMD Athlon 1 GHz review system (review soon) did very well: when I plugged in an
Athlon 800, the chip easily overclocked to 8x112 MHz = 896 MHz.
Changing the FSB is a safe and comfortable way to overclock your Athlon. You simply change the FSB value in the bios, and if it doesn't work, the bios will reset to the default values after a reboot.
2) Increase the Multiplier
If you are a bit handy, however, you can try the other way: change the multiplier. You must remove the plastic cover of the Athlon module and connect an overclocking device to the "golden fingers" (in the orange
box) on the Athlon PCB. With such a device you can change the multiplier from 5.0x to 10.5x by flipping a few switches.
The only problem with this approach is removing the small plastic case
of the Athlon module, but we'll show you how.
Not every Athlon is equally overclockable, however. You can greatly improve your overclocking potential by choosing the right chip.
Alternatives
Overclocking the Athlon might seem a daunting task. Are there alternatives
to the Athlon? Yes, there is. The PIII Coppermine 550E (0.18 micron) is
an excellent overclocker which is able to run at 800 MHz. There are a few
caveats, however.
You can not change the multiplier. Just like any Intel chip, is the multiplier locked. This means
you have to raise the Front Side Bus speed, which is limited by chipset,
memory and motherboard quality. Your best option is a motherboard
based on the VIA Apollo 133A chipset, which enables you run your memory
sticks at 3/4 FSB frequency. In order to reach 145 MHz, necessary to clock
the PIII 550E at 800 MHz (5.5x 145), you can clock your memory sticks
at 108 MHz. I hope to test this soon, but the number of motherboards that
reach 145 MHz FSB and higher are quite limited.
Hardware one seemed to be very enthusiastic article about the MSI-6309.
Back to the Athlon, how do you choose the best chip? Read on.
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