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Athlon Thunderbird Overclocking (Page 2/5)


Posted: September 4, 2000
Written by: Tuan "Solace" Nguyen

Overclocking

How does a pencil connect the golden bridges on the Athlon? Because the graphite acts a conductor and it lets small amounts of electrical current flow through from one end of the gold bridge to the other. The L1 brides are the ones that let you change core multiplier. Previously, with Slot A Athlons, you could overclock the processors using Golden Finger devices that attach to the processor itself. Since the Golden Finger connector isnít available anymore and it is quite impossible with the socket processors, you wonít be able to overclock them using any external device.

So what is a power hungry user to do? With the release of Socket A Athlons, AMD declared that its Socket A processors will be clock locked (meaning you cannot adjust the clock multiplier up or down) and users will only be able to overclock the processor by adjusting the front-side bus. While Intel had locked its processors for a long time, the Socket A Athlons mark the first time AMD has done such a thing.

You may be thinking that all hope is lost; but AMD has implemented its clock locks more loosely than Intel. On the socket Athlons there are golden bridges that are unlinked electrical connects that when connected or disconnected will enable or disable a feature.



Above you see a diagram showing the locked an unlocked L1 bridges on the Athlon. There are processors out there on the market that actually have their clocks unlocked. This is surprising since AMD said that its processors would be locked. But what can I say? This is better for everyone.

The Ways of the Overclocker

Now that weíve unlocked the clock multiplier on the Thunderbird, there are three methods to overclock this chip. The first method is to use the clock multiplier.

Here, we are using an 800MHz Thunderbird. This chip runs on a 100MHz Front-side Bus multiplied by an 8x clock setting. You can overclock the CPU by changing the multiplier to letís say 9x. That would give you 900MHz. That method was the most common method until Intel introduced the clock lock circuitry in its processors. Now that AMD is following that same path, it makes it harder for us performance freaks to eek out more juice from our processors. Luckily AMD left a back door with the L1 bridges.

Overclocking using FSB

Why did I just say the Athlon runs on a 100MHz FSB when clearly everyone knows that it runs on a 200MHz FSB? This is because the Athlon is based on a double-data rate bus, just like DDR SDRAM. Data is transferred on both the rising and falling clock cycles, effectively creating a 200MHz FSB. Keeping this in mind, overclocking your FSB by just a few MHz will result in twice that speed. For example, the default is 100MHz and you want to go to a small jump of 5MHz to 105MHz. Well since itís double-data rate, you effectively reach 210MHz. Thatís an entire 10MHz jump, which is a lot. For those of you who have speedy RAM and want to go to something like 224MHz, think twice about that one.

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