Athlon 64 Overclocking

Overclocking 101

The exact overclocking procedure depends a lot on the motherboard you are using, since each motherboard has its own set of available options. We will try to be as much generic as we can, giving information that can be applied to all motherboards found on the market.
Basically you will need to:

1. Lock the clock of all other devices but the CPU with their default clock rates, if your motherboard provides this option.
2. Change the CPU base clock configuration from “auto” to “manual”, if necessary.
3. Increase the CPU base clock step by step checking if your system is still running stable.
4. Change the HyperTransport bus clock multiplier from x5 to x4 once you surpassed the 220 MHz clock rate, if your motherboard provides this option and you use a CPU with 1,000 MHz HyperTransport bus (a.k.a. “2,000 MHz” or “4 GB/s”).
5. Change the HyperTransport bus clock multiplier from x4 to x3 once you surpassed the 225 MHz clock rate, if your motherboard provides this option and you use a CPU with 800 MHz HyperTransport bus (a.k.a. “1,600 MHz” or “3.2 GB/s”).
6. Change the HyperTransport bus clock multiplier from x4 to x3 once you surpassed the 275 MHz clock rate (if you are that lucky) if your motherboard provides this option and you use a CPU with 1,000 MHz HyperTransport bus (a.k.a. “2,000 MHz” or “4 GB/s”).
7. Change the HyperTransport bus clock multiplier from x3 to x2 once you surpassed the 300 MHz clock rate (if you are that lucky), if your motherboard provides this option and you use a CPU with 800 MHz HyperTransport bus (a.k.a. “1,600 MHz” or “3.2 GB/s”).

This is done at the motherboard setup, pressing Del just after turning on your PC. The exact name and location of each option varies a lot, so we will give some real examples.
In Figure 3 you see the setup of Biostar K8VHA Pro, which provides just one overclocking option – changing the CPU base clock. Most low-end motherboards will provide only this option, making it hard to go an overclocking over 225 MHz, as all other motherboards components will be overclocked as well.

Figure 3: CPU overclocking on an entry-level motherboard (Biostar K8VHA Pro).

On Figures 4 and 5 you see an older AGP-based motherboard, EPoX 8KDA3+, which has more overclocking options than the previous board. As you can see, on this motherboard you can configure the AGP bus clock individually, i.e., you can lock it at 66 MHz. On this motherboard you can also configure the HyperTransport bus clock multiplier, but this option is hidden under “Advanced Chipset Features”, and one may not correlate this option with overclocking.

Figure 4: CPU overclocking on an older AGP-based motherboard (EPoX 8KDA3+).

Figure 5: HyperTransport clock multiplier configuration (EPoX 8KDA3+).